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Peripheral T-Cell Lymphoma: Spectrum of Imaging Findings with Clinical and Pathologic Features

Abstract

Most radiologists are unfamiliar with peripheral T-cell lymphoma (PTCL) because PTCL represents a relatively small proportion of lymphomas and has a lower prevalence in Western countries. The World Health Organization classification of lymphoid neoplasms announced in 1999 resolved criticisms about lymphoma classification and aroused new interest in PTCL. The specific clinicopathologic entities of PTCL have particular primary locations and particular clinical and pathologic features. Radiologic images of patients with pathologically proved PTCL were retrospectively reviewed; clinical and pathologic data were also reviewed. PTCL involves various organs including the sinonasal cavity, airway, intestinal tract, skin, lymph nodes, liver, lung, and musculoskeletal system. The pattern of disease involvement in PTCL is not random. There is a correlation between specific clinicopathologic entities and the primary site of involvement, although the findings in the disseminated stage of disease do not allow differential diagnosis. It is significant that the radiologic features or locations of several entities are different from those of lymphoma with the B-cell phenotype. Radiologic demonstration of disease progression beyond the primary site is clinically important because systemic dissemination in most of the entities leads to a dramatic change in the prognosis.

LEARNING OBJECTIVES FOR TEST 1

After reading this article and taking the test, the reader will be able to:

•.	Recognize the radiologic appearances of the specific clinicopathologic entities of PTCL on radiographs and CT, MR, and barium images.
•.	List the clinical and pathologic features of PTCL.
•.	Describe the new classification system and diagnostic criteria for PTCL.

Introduction

Most radiologists are unfamiliar with peripheral T-cell lymphoma (PTCL) because PTCL represents a relatively small proportion of lymphomas and has a lower prevalence in Western countries. To our knowledge, there is no overview of the clinical, pathologic, and radiologic features of PTCL. We retrospectively reviewed radiologic studies of patients with pathologically proved PTCL; clinical and pathologic data were also reviewed.

This article presents an overview of the important clinical, pathologic, and radiologic features of the specific clinicopathologic entities of PTCL. Classification and diagnosis of PTCL and the clinical outcome of PTCL are also discussed. We hope that this article familiarizes many radiologists with this complex disease.

Classification and Diagnosis

Histologic categorization of lymphomas has been a source of frustration for many years for both clinicians and pathologists. Increased understanding of the immune system and the genetic abnormalities associated with non-Hodgkin lymphoma have led to identification of several previously unrecognized types of lymphoma. The recognition of these new types of clinically relevant lymphomas led to proposals for changing existing classifications. In the new World Health Organization (WHO) classification, the most practical approach to lymphoma categorization was performed, which simply defined the diseases that we can recognize with the currently available clinical, morphologic, immunologic, and genetic techniques (^,1–^,5). This classification was based on the proposal for a revised European-American classification of lymphoid neoplasms (REAL classification) (^,6). In the WHO classification, there is no single standard of reference for categorization of lymphomas. It simply defines the diseases by using the currently available clinical, morphologic, immunologic, and genetic techniques. The importance of criteria for both definition and diagnosis differs among different entities. Thus, the lymphoma classification becomes simply a list of well-defined “real” clinical syndromes, that is, several clinicopathologic entities (^,1–^,5). This is the most important merit of the WHO classification compared with previously used classification systems, including the Working Formulation classification system in North America and the Kiel classification in Europe, which were mainly based on cellular morphology and immunologic findings.

In the WHO classification, lymphoid malignancies are divided largely into T-cell neoplasms, B-cell neoplasms, and Hodgkin disease. T-cell neoplasms are divided into precursor T-cell neoplasms and peripheral T-cell neoplasms. B-cell neoplasms are divided in the same manner. The peripheral T-cell neoplasms are informally grouped according to their major clinical presentations: predominantly disseminated/leukemic disease, primary extranodal disease, and predominantly nodal disease (^,1–^,5). Among the peripheral T-cell neoplasms, primary extranodal disease and predominantly nodal disease are referred to as peripheral T-cell lymphoma. PTCL accounts for approximately 25% of all non-Hodgkin lymphomas in Korea and approximately 10%–15% in Europe (^,7–^,9). A number of distinct clinicopathologic entities are included in this disorder (^,Table 1).

For the diagnosis and subclassification of PTCL, cytologic composition (small, large, anaplastic), immunophenotypic features (positivity to specific immunologic markers such as CD3, CD4, CD8, etc), and cytogenetic features should be considered at the same time. In some cases, demonstration of a monoclonal T-cell population by using T-cell receptor gene rearrangement studies will be required to make a diagnosis. Above all, the particular primary location and clinical syndromes appear to be essential to the definition of PTCL (^,1–^,5).

Clinical Outcome

The prognosis of patients with non-Hodgkin lymphoma is best assigned by using the International Prognostic Index (IPI) (^,Table 2), which is a powerful predictor of outcome in all subtypes of non-Hodgkin lymphoma. Patients are assigned an IPI score based on the presence or absence of five adverse prognostic factors and may have none or all five of these factors (^,10). Unfortunately, patients with PTCL usually present with adverse prognostic factors, with 80% of patients having an IPI score of 2 and 30% having an IPI score of 4 (^,10). As would be predicted, PTCLs are associated with a poor outcome, and only 25% of patients survive 5 years after diagnosis. Treatment regimens are the same as those used for diffuse large B-cell lymphoma, but patients with PTCL have a poorer response to treatment (^,10).

Recently, multivariate analysis showed that the IPI score and the T-cell phenotype are totally independent and are the most significant predictors of failure-free survival and overall survival (^,11). Therefore, immunophenotypic classification of lymphoma into T-cell lymphoma and B-cell lymphoma is clinically relevant, and the T-cell phenotype is an independent and significant poor prognostic factor (^,11).

Specific Clinicopathologic Entities

Extranodal NK/T-Cell Lymphoma, Nasal Type

Clinical Features.—

Extranodal NK/T-cell lymphoma of the nasal type has also been called angiocentric lymphoma and was previously termed lethal midline granuloma or polymorphic reticulosis (^,12,^,13). This disorder is more common in Asia and South America than in the United States and Europe. It accounts for approximately 12% of all non-Hodgkin lymphomas in Korea and approximately 2% in Europe (^,7,^,9). Nearly half (45%) of all malignant lymphomas of the nasal cavity and nasopharynx are derived from NK/T cells, whereas 21% are derived from T cells and 34% are derived from B cells (^,14). This disease presents clinically as a lethal midline granuloma or midfacial destructive lesion. The nose is the most frequently involved, and other extranodal sites including the palate and upper airway are other primary involved sites (^,Table 3). Few cases occur in areas other than the nose, and these are referred to as non–nasal type NK/T-cell lymphoma. The course is aggressive, and the overall outlook is poor (^,10,^,15–^,17).

Pathologic Features.—

“Angiocentric” invasion of lymphoid cells is characteristic of this disorder (^,^,^,^,Fig 1a). Angiocentricity is seen in about half of all cases but is also found in other lymphoma subtypes. Invasion of vascular walls by lymphoid cells causes occlusion of the lumen. The vascular occlusion is usually associated with prominent ischemic necrosis of both tumor cells and normal tissue. Despite the characteristic pathologic features of nasal NK/T-cell lymphoma, difficulty in the diagnosis of this disorder, both clinically and pathologically, is well recognized. Pathologic differentiation from chronic inflammation is difficult because atypical lymphoma cells and inflammatory lymphocytes mix at the site of ischemic necrosis. This lymphoma is highly associated with Epstein-Barr viral infection, and the immunophenotypic profile of the tumor cells is CD2+, CD56+ (natural killer cell marker), and CD3− (^,^,^,^,Fig 1b, ^,^,^,^,1c). Genotypically, the T-cell receptor gene in germ line configuration allows classification (^,10,^,15–^,17).

Radiologic Features.—

Little is known about the imaging features of extranodal NK/T-cell lymphoma of the nasal type. Patients with nasal NK/T-cell lymphoma frequently present with tumor confined to the nasal cavity. The tumor shows a predilection for diffuse invasion of the nasal cavity (^,^,^,^,Fig 2), often involving both sides. In smaller-volume lymphomas, there is a tendency for spread as a diffuse thin sheet of tumor along the walls of the nasal cavity to envelop the nasal turbinates and nasal septum. In larger-volume disease, a more discernible mass is seen with occasional spread to the nasopharynx or palate. Destruction of the midline structures—the nasal turbinates, nasal septum, and palate—occurs in half of patients, and tumor necrosis is frequently detected at computed tomography (CT) or magnetic resonance (MR) imaging (^,^,^,^,Fig 2) (^,18–^,20). Regional nodal enlargement is rare. The CT and MR imaging appearances are nonspecific and do not allow reliable distinction of this disease from other nasal cavity tumors such as squamous cell carcinoma or from minor salivary gland tumor. Nonneoplastic conditions including Wegener granulomatosis, sarcoidosis, and fungal infections should be differentiated. It is generally accepted that most lymphomas that originate from the maxillary sinus are B-cell lymphomas with a good prognosis and those that originate from the nasal cavity or ethmoid sinus are PTCLs causing early death (^,21). Therefore, it is important to accurately define the primary site of sinonasal lymphoma with an imaging modality. Although such involvement is rare, the upper airway such as the larynx and trachea could be involved. The luminal narrowing and wall thickening in these organs could be detected at radiography and CT (^,^,^,^,Fig 3).

Enteropathy-type T-Cell Lymphoma

Clinical Features.—

Enteropathy-type intestinal T-cell lymphoma is a rare disorder. Although it usually occurs in patients with untreated gluten-sensitive enteropathy, it can occur in persons without enteropathy. It accounts for less than 1% of all non-Hodgkin lymphomas in Asia and Europe (^,7,^,9). It most frequently involves the small intestine; however, it could involve the colon and stomach. The course is aggressive, and death is usually due to multifocal intestinal perforation caused by refractory malignant ulcers. The prognosis is poor (^,1–^,6).

Pathologic Features.—

At gross examination, multiple intestinal ulcers are present, often with perforation. Pathologic differentiation from inflammatory bowel disease is difficult. Microscopically, atypical lymphoma cells and inflammatory lymphocytes mix at the site of mucosal ulceration (^,Fig 4). Thus, if biopsy is performed at the areas that predominantly have inflammatory lymphocytes, the pathologic diagnosis may be inflammatory bowel disease rather than lymphoma (^,21–^,23).

Radiologic Features.—

Reports on the radiologic features of enteropathy-type T-cell lymphoma are rare. Recently, the radiographic manifestations of colonic PTCL were reported (^,24). In that report, PTCL of the colon manifested as a diffuse or focal segmental lesion and showed extensive mucosal ulceration at double-contrast barium enema examination. These findings are similar to those of inflammatory bowel disease and different from those of colorectal lymphoma of the B-cell phenotype (^,^,^,^,^,Figs 5, ^,^,^,^,^,6). Because radiologic and pathologic diagnosis of PTCL in the intestine is difficult, clinical suspicion is important. PTCL should be suspected in the patient who has the radiologic features of inflammatory bowel disease with extensive ulcers that are refractory to treatment. Also, if there are shallow large irregular ulcers in multiple locations, the diagnosis of PTCL might be considered. Repeated endoscopic biopsies at multiple sites and immunohistochemical staining are frequently warranted to make a definitive diagnosis.

Mycosis Fungoides/Sézary Syndrome

Clinical Features.—

Mycosis fungoides is also known as cutaneous T-cell lymphoma. This lymphoma is more often seen by dermatologists. The disorder is more common in males and in blacks (^,10). It accounts for approximately 6% of all non-Hodgkin lymphomas in Europe and is rare in Asian countries (^,7,^,9). Mycosis fungoides is an indolent lymphoma, with patients often having several years of eczematous or dermatitic skin lesions before the diagnosis is finally established. The skin lesions progress from the patch stage to the plaque stage to cutaneous tumors (^,Fig 7). Patients have been treated with radiation therapy, topical glucocorticoids, topical nitrogen mustard, phototherapy, psoralen with ultraviolet A, electron beam radiation, interferon, and systemic cytotoxic therapy. Unfortunately, these treatments are palliative. In its later stages, mycosis fungoides can cause peripheral lymphadenopathy and finally progress to widespread extracutaneous visceral involvement. Extracutaneous involvement causes a dramatic change in the 5-year survival rate, which drops from 90% with skin disease to 50% with nodal involvement and to near 0% with systemic spread (^,1–^,5,^,10,^,25).

Pathologic Features.—

Epidermotropism of solitary lymphocytes or a small intraepidermal collection of lymphocytes (the so-called Pautrier microabscess) can be seen in early patchy lesions. Intraepidermal lymphocytes are usually neither strikingly atypical nor notably larger than those in the superficial dermis (^,Fig 8). In the tumor stage, the normal structure of the skin is usually destroyed (^,25).

Radiologic Features.—

The cutaneous lesions including patches, plaques, or erythroderma show no abnormalities at CT. In the stage of tumor formation, thickening or a mass of the skin is seen at CT (^,^,^,^,Figs 9, ^,^,^,^,^,10). The imaging features of mycosis fungoides are nonspecific, and differentiation from cutaneous involvement by other diseases including T-cell leukemia and from connective tissue disease is frequently not possible (^,26,^,27). Evaluation of extracutaneous involvement, disease progression, and stage is the most important role of imaging in mycosis fungoides. For these reasons, CT demonstration of clinically unsuspected lymphadenopathy or abnormality in visceral organs such as hepatosplenomegaly is important.

Subcutaneous Panniculitis-like T-Cell Lymphoma

Clinical Features.—

Subcutaneous panniculitis-like T-cell lymphoma is a rare disorder. Clinically, it is often confused with inflammatory panniculitis associated with connective tissue disease. Patients usually present with multiple palpable subcutaneous nodules. The nodules can progress and ulcerate. Two clinical courses are reportedly observed: a prolonged course of recurrent panniculitis or rapid clinical deterioration secondary to the hemophagocytic syndrome (profound anemia, ingestion of erythrocytes by monocytes and macrophages). Development of the hemophagocytic syndrome generally leads to a fatal outcome (^,1–^,5,^,10).

Pathologic Features.—

Histologically, subcutaneous panniculitis-like T-cell lymphoma is characterized by a lymphohistiocytic infiltrate confined primarily to the fat lobules in subcutaneous tissue. Lymphoid cells commonly surround individual adipocytes (^,^,^,Fig 11a). Karyorrhexis, fat necrosis, and cytophagocytosis are frequently seen (^,25).

Radiologic Features.—

Multiple subcutaneous nodules in patients with subcutaneous panniculitis-like T-cell lymphoma are well recognized at CT as multiple enhancing nodules (^,^,^,Fig 11b). Radiologic differential diagnoses could include inflammatory panniculitis associated with systemic lupus erythematosus or rheumatoid arthritis, cutaneous metastasis in malignant melanoma or breast cancer, and unusual subcutaneous nodules originating from a bacterial, fungal, or parasitic infection.

Anaplastic Large Cell Lymphoma, Primary Cutaneous Type

Clinical Features.—

Anaplastic large cell lymphoma (ALCL) can be further divided into subgroups based on the initial site of anatomic presentation: systemic or cutaneous Ki-1+ ALCL. Compared with systemic ALCL, cutaneous Ki-1+ ALCL has a more indolent clinical course. Cutaneous ALCL usually occurs in older adults. Spontaneous regression has been noted in a few patients (^,1–^,5,^,10). Cutaneous lesions of Ki-1+ ALCL typically manifest as solitary or multiple ulcerated nodules or plaques (^,25).

Pathologic Features.—

Histologically, cutaneous ALCL lesions typically consist of a diffuse dermal and subcutaneous infiltrate composed of large, bizarre, pleomorphic cells with Reed-Sternberg–like cells. These cells contain irregular nuclei with prominent nucleoli and have abundant amphophilic to basophilic cytoplasm. The cells grow in a cohesive pattern and often preferentially cause perineural and perivascular invasion (^,^,^,Fig 12) (^,25).

Radiologic Features.—

The radiology literature on cutaneous ALCL is nearly absent. In our experience, early lesions such as patches or plaques show no abnormalities at CT. In the stage of tumor formation, thickening or a mass of the skin is seen at CT (^,^,^,^,^,Fig 13). As in mycosis fungoides, the important role of imaging is evaluation of involvement of visceral organs such as the lung, lymph nodes, and gastrointestinal tract.

Anaplastic Large Cell Lymphoma, Primary Systemic Type

Clinical Features.—

ALCL accounts for 1.5%–3% of all non-Hodgkin lymphomas in Asia and Europe (^,7,^,9). Patients with systemic ALCL are typically young and male. A common clinical presentation is generalized extensive lymphadenopathy. Extranodal sites could be involved, including bone, soft tissue, and the skin, lung, pleura, gastrointestinal tract, and infrequently bone marrow. Patients most commonly present with disseminated stage disease. Some patients with disease confined to the skin have a different and more indolent disorder that has been termed cutaneous ALCL (^,10).

Pathologic Features.—

In the past, ALCL was usually diagnosed as undifferentiated carcinoma or malignant histiocytosis. Discovery of the Ki-1 antigen led to identification of a new type of lymphoma (^,^,^,^,^,^,^,Fig 14a, ^,^,^,^,^,^,^,14b). Some of the previously unclassified malignancies displayed this antigen. Subsequently, discovery of the chromosomal translocation t(2;5) and the resultant frequent overexpression of the anaplastic lymphoma kinase (alk) protein confirmed the existence of this entity (^,1–^,6,^,25). The diagnosis of ALCL is made when an expert hematopathologist recognizes typical pleomorphic cells that contain irregular nuclei and prominent nucleoli. Documentation of Ki-1 positivity, t(2;5), and/or overexpression of the alk protein confirms the diagnosis (^,25).

Radiologic Features.—

Because patients most commonly present with disseminated conditions, an initial imaging work-up that covers the whole body is important as well as pathologic confirmation. Plain chest radiography, CT, radionuclear scintigraphy, and positron emission tomography are commonly used imaging modalities. In the thorax, mediastinal lymphadenopathy, multiple pulmonary nodules, and pleural or pericardial effusions are frequently seen. In systemic ALCL, pleural or pericardial mass formation is common. In the abdomen, intraabdominal and retroperitoneal lymph node enlargement, mesenteric infiltration or a mesenteric mass, diffuse intestinal wall thickening, and ascites are seen (^,^,^,^,^,^,^,Fig 14c–^,^,^,^,^,^,^,14f). Peripheral lymph nodes in the axillary, inguinal, and cervical areas are diffusely enlarged in most patients. The brain, spinal cord, and muscles are rarely involved. In the disseminated stage of other subtypes of PTCL such as nasal-type NK/T-cell lymphoma, enteropathy-type T-cell lymphoma, and mycosis fungoides, the radiologic appearance is not distinguished from that in systemic ALCL.

Angioimmunoblastic T-Cell Lymphoma

Clinical Features.—

Angioimmunoblastic T-cell lymphoma is clinically characterized by a high fever, generalized lymphadenopathy, a skin rash, and hepatosplenomegaly. This is a relatively rare disorder but one that is clinically distinctive (^,10). It accounts for less than 1% of all non-Hodgkin lymphomas in Asia and Europe (^,7,^,9). Although this disorder has been regarded as an abnormal immune reaction (angioimmunoblastic lymphadenopathy with dysproteinemia or immunoblastic lymphadenopathy), it is now accepted as a subtype of PTCL. Immunoblastic lymphadenopathy–like T-cell lymphoma is another name for this disorder. Many cases demonstrate aggressive clinical behavior (^,1–^,6).

Pathologic Features.—

Histologically, angioimmunoblastic T-cell lymphoma is characterized by prominent vascular proliferations. Affected lymph nodes show an effaced architecture caused by proliferation of atypical lymphoid cells and arborizing endothelial venules. The infiltrate also contains eosinophils, plasma cells, and occasional immunoblasts (^,^,^,^,^,^,Fig 15a, ^,^,^,^,^,^,15b) (^,25).

Radiologic Features.—

Because patients most commonly present with disseminated conditions, the imaging features are not distinguished from those in other subtypes of lymphoma in the disseminated state (^,^,^,^,^,^,Fig 15c–^,^,^,^,^,^,15e).

Hepatosplenic γδ T-Cell Lymphoma

Clinical Features.—

Hepatosplenic γδ T-cell lymphoma is a rare, recently described subtype of PTCL characterized by hepatosplenomegaly without lymphadenopathy and significant cytopenia. This disorder has an aggressive clinical course and a poor treatment outcome (^,10).

Pathologic Features.—

Lymphoma preferentially involves hepatic sinusoids, splenic red pulp, and bone marrow. By definition, hepatosplenic γδ T-cell lymphoma expresses the γδ T-cell receptor at cytogenetic study (^,1–^,6,^,10).

Radiologic Features.—

To our knowledge, there is no radiology literature on hepatosplenic γδ T-cell lymphoma. Hepatosplenomegaly may be detected at abdominal radiography and CT.

Peripheral T-Cell Lymphoma, Not Otherwise Specified

Cases that do not match one of the defined entities of PTCL are best categorized as “not otherwise specified” (NOS), reflecting the fact that we do not yet understand everything about lymphomas or the immune system. PTCL NOS accounts for approximately 11% of all non-Hodgkin lymphomas in Korea and approximately 4% in Europe (^,7,^,9). This category includes heterogeneous diseases that require further definition.

Clinical Features.—

Patients with PTCL NOS are usually adults with generalized disease; the lymph nodes, liver, and spleen may be involved. The clinical course is usually aggressive, and relapses are more common than in B-cell lymphomas of similar histologic grades.

Pathologic Features.—

Cases with various cellular morphologies including medium-sized cell, mixed medium and large cell, large cell, and lymphoepithelioid cell could be included in this type of PTCL (^,1–^,5).

Radiologic Features.—

Generalized lymphadenopathy is the most common finding. In patients with disseminated conditions, the imaging features are not distinguished from those in other subtypes of lymphoma in the disseminated state.

Conclusions

PTCL is a recently described pathologic entity in a newly developed classification system of lymphoid neoplasms. PTCL can demonstrate a wide spectrum of disease in many organs. Specific clinicopathologic entities of PTCL have a particular primary location and particular clinical and pathologic features. Most radiologic features of PTCL are nonspecific and often simulate those of other neoplasms or inflammatory conditions. However, it is significant that the radiologic features and locations of several entities including enteropathy-type T-cell lymphoma and nasal-type NK/T-cell lymphoma are different from those of lymphoma with the B-cell phenotype (^,21,^,28–^,30). Radiologic demonstration of disease progression beyond the primary site is also clinically important because systemic dissemination in most of the entities leads to a dramatic change in the prognosis.

**Figure 1a.** Nasal-type extranodal NK/T-cell lymphoma involving the nasal cavity in a 42-year-old woman. **(a)** Photomicrograph (original magnification, ×400; hematoxylin-eosin [H-E] stain) of a nasal mucosal biopsy specimen shows intense infiltration of atypical lymphoid cells into the vascular intima and subintima (arrow). This is a typical appearance of angiocentric invasion in which the vascular lumen *(V)* is nearly obstructed. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of NK-cell marker (CD56)-labeled tissue shows that atypical lymphoid cells react positively with the marker and appear brown. **(c)** Photomicrograph (original magnification, ×600; in situ hybridization of Epstein-Barr virus on paraffin-embedded material) shows cells labeled with Epstein-Barr virus DNA (arrows).

**Figure 1b.** Nasal-type extranodal NK/T-cell lymphoma involving the nasal cavity in a 42-year-old woman. **(a)** Photomicrograph (original magnification, ×400; hematoxylin-eosin [H-E] stain) of a nasal mucosal biopsy specimen shows intense infiltration of atypical lymphoid cells into the vascular intima and subintima (arrow). This is a typical appearance of angiocentric invasion in which the vascular lumen *(V)* is nearly obstructed. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of NK-cell marker (CD56)-labeled tissue shows that atypical lymphoid cells react positively with the marker and appear brown. **(c)** Photomicrograph (original magnification, ×600; in situ hybridization of Epstein-Barr virus on paraffin-embedded material) shows cells labeled with Epstein-Barr virus DNA (arrows).

**Figure 1c.** Nasal-type extranodal NK/T-cell lymphoma involving the nasal cavity in a 42-year-old woman. **(a)** Photomicrograph (original magnification, ×400; hematoxylin-eosin [H-E] stain) of a nasal mucosal biopsy specimen shows intense infiltration of atypical lymphoid cells into the vascular intima and subintima (arrow). This is a typical appearance of angiocentric invasion in which the vascular lumen *(V)* is nearly obstructed. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of NK-cell marker (CD56)-labeled tissue shows that atypical lymphoid cells react positively with the marker and appear brown. **(c)** Photomicrograph (original magnification, ×600; in situ hybridization of Epstein-Barr virus on paraffin-embedded material) shows cells labeled with Epstein-Barr virus DNA (arrows).

**Figure 2a.** Nasal-type extranodal NK/T-cell lymphoma in a 40-year-old woman. **(a)** Axial T2-weighted MR image shows a low-signal-intensity mass that fills the left nasal cavity and thickening of the medial wall of the maxillary sinus (arrow). The mass had intermediate signal intensity on T1-weighted MR images. **(b)** Axial contrast material-enhanced MR image shows diffuse enhancement of the mass. Nonenhancement of a portion of the tumor (black arrow) is suggestive of necrosis. Note the thickening and enhancement of the medial wall of the left maxillary sinus (white arrow), an appearance suggestive of tumor infiltration. **(c)** Coronal contrast-enhanced MR image shows diffuse spread of the tumor in the left ethmoid sinus and left nasal cavity.

**Figure 2b.** Nasal-type extranodal NK/T-cell lymphoma in a 40-year-old woman. **(a)** Axial T2-weighted MR image shows a low-signal-intensity mass that fills the left nasal cavity and thickening of the medial wall of the maxillary sinus (arrow). The mass had intermediate signal intensity on T1-weighted MR images. **(b)** Axial contrast material-enhanced MR image shows diffuse enhancement of the mass. Nonenhancement of a portion of the tumor (black arrow) is suggestive of necrosis. Note the thickening and enhancement of the medial wall of the left maxillary sinus (white arrow), an appearance suggestive of tumor infiltration. **(c)** Coronal contrast-enhanced MR image shows diffuse spread of the tumor in the left ethmoid sinus and left nasal cavity.

**Figure 2c.** Nasal-type extranodal NK/T-cell lymphoma in a 40-year-old woman. **(a)** Axial T2-weighted MR image shows a low-signal-intensity mass that fills the left nasal cavity and thickening of the medial wall of the maxillary sinus (arrow). The mass had intermediate signal intensity on T1-weighted MR images. **(b)** Axial contrast material-enhanced MR image shows diffuse enhancement of the mass. Nonenhancement of a portion of the tumor (black arrow) is suggestive of necrosis. Note the thickening and enhancement of the medial wall of the left maxillary sinus (white arrow), an appearance suggestive of tumor infiltration. **(c)** Coronal contrast-enhanced MR image shows diffuse spread of the tumor in the left ethmoid sinus and left nasal cavity.

**Figure 3a.** Nasal-type extranodal NK/T-cell lymphoma involving the larynx and trachea in a 12-year-old girl. **(a, b)** Anteroposterior **(a)** and lateral **(b)** radiographs of the cervical spine show luminal irregularity with narrowing of the upper trachea (arrows). **(c)** CT scan shows diffuse thickening of the tracheal wall (black arrow). The air in the soft tissues on the right side of the neck (white arrows) originated from a tracheostomy.

**Figure 3b.** Nasal-type extranodal NK/T-cell lymphoma involving the larynx and trachea in a 12-year-old girl. **(a, b)** Anteroposterior **(a)** and lateral **(b)** radiographs of the cervical spine show luminal irregularity with narrowing of the upper trachea (arrows). **(c)** CT scan shows diffuse thickening of the tracheal wall (black arrow). The air in the soft tissues on the right side of the neck (white arrows) originated from a tracheostomy.

**Figure 3c.** Nasal-type extranodal NK/T-cell lymphoma involving the larynx and trachea in a 12-year-old girl. **(a, b)** Anteroposterior **(a)** and lateral **(b)** radiographs of the cervical spine show luminal irregularity with narrowing of the upper trachea (arrows). **(c)** CT scan shows diffuse thickening of the tracheal wall (black arrow). The air in the soft tissues on the right side of the neck (white arrows) originated from a tracheostomy.

**Figure 4.** Enteropathy-type T-cell lymphoma involving the colon in a 44-year-old man. Photomicrograph (original magnification, ×200; H-E stain) of a colectomy specimen shows atypical lymphoid cells with abundant cytoplasm (arrowheads) and small inflammatory lymphocytes (arrows) mixed at the site of mucosal ulceration. The pathology report on the initial colonoscopic biopsy specimen concluded that the patient had chronic nonspecific colitis; the diagnosis was confirmed after colonic resection.

**Figure 5a.** Enteropathy-type T-cell lymphoma involving the colon in a 37-year-old man. **(a)** Image from a double-contrast barium enema study shows multiple aphthous ulcers (thin arrows) and segmental luminal narrowing (thick arrows) in the transverse colon. **(b)** Close-up radiograph of the splenic flexure shows multiple irregular ulcers (arrows). **(c)** Photograph from colonoscopy shows an aphthous ulcer in the transverse colon (arrow). After one cycle of chemotherapy, the patient experienced colonic perforation. Segmental resection of the transverse colon was performed. **(d)** Photograph of the pathologic specimen shows segmental luminal irregularity in the transverse colon (white arrows). Multiple aphthous ulcers (black arrows) and the perforation site (arrowhead) are also noted. Scale is in 5-mm intervals.

**Figure 5b.** Enteropathy-type T-cell lymphoma involving the colon in a 37-year-old man. **(a)** Image from a double-contrast barium enema study shows multiple aphthous ulcers (thin arrows) and segmental luminal narrowing (thick arrows) in the transverse colon. **(b)** Close-up radiograph of the splenic flexure shows multiple irregular ulcers (arrows). **(c)** Photograph from colonoscopy shows an aphthous ulcer in the transverse colon (arrow). After one cycle of chemotherapy, the patient experienced colonic perforation. Segmental resection of the transverse colon was performed. **(d)** Photograph of the pathologic specimen shows segmental luminal irregularity in the transverse colon (white arrows). Multiple aphthous ulcers (black arrows) and the perforation site (arrowhead) are also noted. Scale is in 5-mm intervals.

**Figure 5c.** Enteropathy-type T-cell lymphoma involving the colon in a 37-year-old man. **(a)** Image from a double-contrast barium enema study shows multiple aphthous ulcers (thin arrows) and segmental luminal narrowing (thick arrows) in the transverse colon. **(b)** Close-up radiograph of the splenic flexure shows multiple irregular ulcers (arrows). **(c)** Photograph from colonoscopy shows an aphthous ulcer in the transverse colon (arrow). After one cycle of chemotherapy, the patient experienced colonic perforation. Segmental resection of the transverse colon was performed. **(d)** Photograph of the pathologic specimen shows segmental luminal irregularity in the transverse colon (white arrows). Multiple aphthous ulcers (black arrows) and the perforation site (arrowhead) are also noted. Scale is in 5-mm intervals.

**Figure 5d.** Enteropathy-type T-cell lymphoma involving the colon in a 37-year-old man. **(a)** Image from a double-contrast barium enema study shows multiple aphthous ulcers (thin arrows) and segmental luminal narrowing (thick arrows) in the transverse colon. **(b)** Close-up radiograph of the splenic flexure shows multiple irregular ulcers (arrows). **(c)** Photograph from colonoscopy shows an aphthous ulcer in the transverse colon (arrow). After one cycle of chemotherapy, the patient experienced colonic perforation. Segmental resection of the transverse colon was performed. **(d)** Photograph of the pathologic specimen shows segmental luminal irregularity in the transverse colon (white arrows). Multiple aphthous ulcers (black arrows) and the perforation site (arrowhead) are also noted. Scale is in 5-mm intervals.

**Figure 6a.** Enteropathy-type T-cell lymphoma involving the terminal ileum in a 61-year-old man. **(a)** Image from a barium study of the small intestine shows a linear ulcer (arrows) along the mesenteric border in the terminal ileum. **(b)** Close-up radiograph of the terminal ileum shows a pseudosacculation (open arrows) along the antimesenteric border and a linear ulcer (solid arrows) along the mesenteric border in the terminal ileum. **(c)** CT scan shows wall thickening in the terminal ileum (arrow) and mesenteric fat infiltration around the ileum. **(d)** Photograph of the ileocecectomy specimen shows multiple irregular ulcers (arrows) in the terminal ileum. The prospective radiologic diagnosis was Crohn disease on the basis of the linear ulcers and pseudosacculation of the terminal ileum. Moreover, the pathologic diagnosis after the initial ileal biopsy was chronic nonspecific ileitis. The diagnosis was confirmed with surgical resection of the intestine. Scale is in 5-mm intervals.

**Figure 6b.** Enteropathy-type T-cell lymphoma involving the terminal ileum in a 61-year-old man. **(a)** Image from a barium study of the small intestine shows a linear ulcer (arrows) along the mesenteric border in the terminal ileum. **(b)** Close-up radiograph of the terminal ileum shows a pseudosacculation (open arrows) along the antimesenteric border and a linear ulcer (solid arrows) along the mesenteric border in the terminal ileum. **(c)** CT scan shows wall thickening in the terminal ileum (arrow) and mesenteric fat infiltration around the ileum. **(d)** Photograph of the ileocecectomy specimen shows multiple irregular ulcers (arrows) in the terminal ileum. The prospective radiologic diagnosis was Crohn disease on the basis of the linear ulcers and pseudosacculation of the terminal ileum. Moreover, the pathologic diagnosis after the initial ileal biopsy was chronic nonspecific ileitis. The diagnosis was confirmed with surgical resection of the intestine. Scale is in 5-mm intervals.

**Figure 6c.** Enteropathy-type T-cell lymphoma involving the terminal ileum in a 61-year-old man. **(a)** Image from a barium study of the small intestine shows a linear ulcer (arrows) along the mesenteric border in the terminal ileum. **(b)** Close-up radiograph of the terminal ileum shows a pseudosacculation (open arrows) along the antimesenteric border and a linear ulcer (solid arrows) along the mesenteric border in the terminal ileum. **(c)** CT scan shows wall thickening in the terminal ileum (arrow) and mesenteric fat infiltration around the ileum. **(d)** Photograph of the ileocecectomy specimen shows multiple irregular ulcers (arrows) in the terminal ileum. The prospective radiologic diagnosis was Crohn disease on the basis of the linear ulcers and pseudosacculation of the terminal ileum. Moreover, the pathologic diagnosis after the initial ileal biopsy was chronic nonspecific ileitis. The diagnosis was confirmed with surgical resection of the intestine. Scale is in 5-mm intervals.

**Figure 6d.** Enteropathy-type T-cell lymphoma involving the terminal ileum in a 61-year-old man. **(a)** Image from a barium study of the small intestine shows a linear ulcer (arrows) along the mesenteric border in the terminal ileum. **(b)** Close-up radiograph of the terminal ileum shows a pseudosacculation (open arrows) along the antimesenteric border and a linear ulcer (solid arrows) along the mesenteric border in the terminal ileum. **(c)** CT scan shows wall thickening in the terminal ileum (arrow) and mesenteric fat infiltration around the ileum. **(d)** Photograph of the ileocecectomy specimen shows multiple irregular ulcers (arrows) in the terminal ileum. The prospective radiologic diagnosis was Crohn disease on the basis of the linear ulcers and pseudosacculation of the terminal ileum. Moreover, the pathologic diagnosis after the initial ileal biopsy was chronic nonspecific ileitis. The diagnosis was confirmed with surgical resection of the intestine. Scale is in 5-mm intervals.

**Figure 7.** Mycosis fungoides in a 36-year-old woman. Photograph shows a cutaneous erythematous plaque (solid arrows) and a cutaneous tumor (open arrows). This appearance represents a typical gross morphology of mycosis fungoides.

**Figure 8.** Mycosis fungoides in a 63-year-old woman. Photomicrograph (original magnification, ×200; H-E stain) of a skin biopsy specimen shows prominent epidermotropism of lymphocytes (arrows). Note the lack of striking nuclear atypia of the intraepidermal lymphocytes. D = dermis, E = epidermis.

**Figure 9a.** Mycosis fungoides in a 51-year-old man. **(a)** CT scan shows a large tumor (open arrows) in the anterior abdominal wall. The tumor involves the skin and subcutaneous fat. A small air bubble suggestive of an ulcer (solid arrow) is also noted. **(b)** Photograph shows an ulcerated cutaneous tumor (arrows). Superficial ulceration of a cutaneous tumor represents an atypical gross morphology of mycosis fungoides. **(c)** Sagittal contrast-enhanced MR image shows another mass on the medial side of the plantar surface (arrow). The mass demonstrates mild homogeneous enhancement. The mass had intermediate signal intensity on T2-weighted images and low signal intensity on T1-weighted images.

**Figure 9b.** Mycosis fungoides in a 51-year-old man. **(a)** CT scan shows a large tumor (open arrows) in the anterior abdominal wall. The tumor involves the skin and subcutaneous fat. A small air bubble suggestive of an ulcer (solid arrow) is also noted. **(b)** Photograph shows an ulcerated cutaneous tumor (arrows). Superficial ulceration of a cutaneous tumor represents an atypical gross morphology of mycosis fungoides. **(c)** Sagittal contrast-enhanced MR image shows another mass on the medial side of the plantar surface (arrow). The mass demonstrates mild homogeneous enhancement. The mass had intermediate signal intensity on T2-weighted images and low signal intensity on T1-weighted images.

**Figure 9c.** Mycosis fungoides in a 51-year-old man. **(a)** CT scan shows a large tumor (open arrows) in the anterior abdominal wall. The tumor involves the skin and subcutaneous fat. A small air bubble suggestive of an ulcer (solid arrow) is also noted. **(b)** Photograph shows an ulcerated cutaneous tumor (arrows). Superficial ulceration of a cutaneous tumor represents an atypical gross morphology of mycosis fungoides. **(c)** Sagittal contrast-enhanced MR image shows another mass on the medial side of the plantar surface (arrow). The mass demonstrates mild homogeneous enhancement. The mass had intermediate signal intensity on T2-weighted images and low signal intensity on T1-weighted images.

**Figure 10a.** Mycosis fungoides in a 52-year-old woman. **(a)** Axial T2-weighted MR image shows a large tumor (arrows) involving the right upper eyelid. The tumor has low signal intensity and involves the skin and subcutaneous tissue. **(b)** Axial T1-weighted MR image shows that the mass has intermediate signal intensity (arrows). **(c)** Axial MR image obtained after injection of gadopentetate dimeglumine shows that the mass has diffuse marked enhancement (arrows). **(d)** CT scan obtained at the level of the hypopharynx shows enlarged lymph nodes in the submental area (thin solid arrows), submandibular area (open arrows), retropharyngeal area (thick solid arrow), and right spinal accessory chain (arrowhead). Laryngeal edema and edematous infiltration into the subcutaneous fat are also seen. Biopsy of the tumor and lymph nodes was performed. Pathologic analysis demonstrated mycosis fungoides involving the skin, subcutaneous tissue, and lymph nodes. Therefore, the patient had stage IV disease (T3 N3).

**Figure 10b.** Mycosis fungoides in a 52-year-old woman. **(a)** Axial T2-weighted MR image shows a large tumor (arrows) involving the right upper eyelid. The tumor has low signal intensity and involves the skin and subcutaneous tissue. **(b)** Axial T1-weighted MR image shows that the mass has intermediate signal intensity (arrows). **(c)** Axial MR image obtained after injection of gadopentetate dimeglumine shows that the mass has diffuse marked enhancement (arrows). **(d)** CT scan obtained at the level of the hypopharynx shows enlarged lymph nodes in the submental area (thin solid arrows), submandibular area (open arrows), retropharyngeal area (thick solid arrow), and right spinal accessory chain (arrowhead). Laryngeal edema and edematous infiltration into the subcutaneous fat are also seen. Biopsy of the tumor and lymph nodes was performed. Pathologic analysis demonstrated mycosis fungoides involving the skin, subcutaneous tissue, and lymph nodes. Therefore, the patient had stage IV disease (T3 N3).

**Figure 10c.** Mycosis fungoides in a 52-year-old woman. **(a)** Axial T2-weighted MR image shows a large tumor (arrows) involving the right upper eyelid. The tumor has low signal intensity and involves the skin and subcutaneous tissue. **(b)** Axial T1-weighted MR image shows that the mass has intermediate signal intensity (arrows). **(c)** Axial MR image obtained after injection of gadopentetate dimeglumine shows that the mass has diffuse marked enhancement (arrows). **(d)** CT scan obtained at the level of the hypopharynx shows enlarged lymph nodes in the submental area (thin solid arrows), submandibular area (open arrows), retropharyngeal area (thick solid arrow), and right spinal accessory chain (arrowhead). Laryngeal edema and edematous infiltration into the subcutaneous fat are also seen. Biopsy of the tumor and lymph nodes was performed. Pathologic analysis demonstrated mycosis fungoides involving the skin, subcutaneous tissue, and lymph nodes. Therefore, the patient had stage IV disease (T3 N3).

**Figure 10d.** Mycosis fungoides in a 52-year-old woman. **(a)** Axial T2-weighted MR image shows a large tumor (arrows) involving the right upper eyelid. The tumor has low signal intensity and involves the skin and subcutaneous tissue. **(b)** Axial T1-weighted MR image shows that the mass has intermediate signal intensity (arrows). **(c)** Axial MR image obtained after injection of gadopentetate dimeglumine shows that the mass has diffuse marked enhancement (arrows). **(d)** CT scan obtained at the level of the hypopharynx shows enlarged lymph nodes in the submental area (thin solid arrows), submandibular area (open arrows), retropharyngeal area (thick solid arrow), and right spinal accessory chain (arrowhead). Laryngeal edema and edematous infiltration into the subcutaneous fat are also seen. Biopsy of the tumor and lymph nodes was performed. Pathologic analysis demonstrated mycosis fungoides involving the skin, subcutaneous tissue, and lymph nodes. Therefore, the patient had stage IV disease (T3 N3).

**Figure 11a.** Subcutaneous panniculitis-like T-cell lymphoma in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×100; H-E stain) shows a lymphoid cell infiltrate in the subcutaneous fat layer. Lymphoid cells surround individual adipocytes *(F)*. **(b)** Abdominal CT scan shows multiple nodules (arrows) in the subcutaneous fat. At gross examination, the subcutaneous nodules gave rise to superficial elevated lesions on the skin.

**Figure 11b.** Subcutaneous panniculitis-like T-cell lymphoma in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×100; H-E stain) shows a lymphoid cell infiltrate in the subcutaneous fat layer. Lymphoid cells surround individual adipocytes *(F)*. **(b)** Abdominal CT scan shows multiple nodules (arrows) in the subcutaneous fat. At gross examination, the subcutaneous nodules gave rise to superficial elevated lesions on the skin.

**Figure 12a.** Primary cutaneous type ALCL in a 63-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a skin biopsy specimen shows infiltration of atypical lymphoid cells with a perineural distribution into the dermis. N = nerve. **(b)** Photomicrograph (original magnification, ×200; H-E stain) shows scattered large lymphoid cells (ie, anaplastic large cells) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm (arrows).

**Figure 12b.** Primary cutaneous type ALCL in a 63-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a skin biopsy specimen shows infiltration of atypical lymphoid cells with a perineural distribution into the dermis. N = nerve. **(b)** Photomicrograph (original magnification, ×200; H-E stain) shows scattered large lymphoid cells (ie, anaplastic large cells) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm (arrows).

**Figure 13a.** Primary cutaneous type ALCL in a 61-year-old man. **(a)** Axial T2-weighted MR image shows a mass (arrows) in the right eyelid. The mass has intermediate signal intensity. **(b)** Axial T1-weighted MR image shows that the mass has homogeneous low signal intensity (arrows). **(c)** Axial fat-suppressed T1-weighted MR image obtained after administration of gadopentetate dimeglumine shows homogeneous enhancement of the mass (arrows). **(d)** Photograph shows a round elevated erythematous tumor involving the right lower eyelid. A central superficial ulcer and crust are noted; these represent the typical gross morphology of cutaneous ALCL.

**Figure 13b.** Primary cutaneous type ALCL in a 61-year-old man. **(a)** Axial T2-weighted MR image shows a mass (arrows) in the right eyelid. The mass has intermediate signal intensity. **(b)** Axial T1-weighted MR image shows that the mass has homogeneous low signal intensity (arrows). **(c)** Axial fat-suppressed T1-weighted MR image obtained after administration of gadopentetate dimeglumine shows homogeneous enhancement of the mass (arrows). **(d)** Photograph shows a round elevated erythematous tumor involving the right lower eyelid. A central superficial ulcer and crust are noted; these represent the typical gross morphology of cutaneous ALCL.

**Figure 13c.** Primary cutaneous type ALCL in a 61-year-old man. **(a)** Axial T2-weighted MR image shows a mass (arrows) in the right eyelid. The mass has intermediate signal intensity. **(b)** Axial T1-weighted MR image shows that the mass has homogeneous low signal intensity (arrows). **(c)** Axial fat-suppressed T1-weighted MR image obtained after administration of gadopentetate dimeglumine shows homogeneous enhancement of the mass (arrows). **(d)** Photograph shows a round elevated erythematous tumor involving the right lower eyelid. A central superficial ulcer and crust are noted; these represent the typical gross morphology of cutaneous ALCL.

**Figure 13d.** Primary cutaneous type ALCL in a 61-year-old man. **(a)** Axial T2-weighted MR image shows a mass (arrows) in the right eyelid. The mass has intermediate signal intensity. **(b)** Axial T1-weighted MR image shows that the mass has homogeneous low signal intensity (arrows). **(c)** Axial fat-suppressed T1-weighted MR image obtained after administration of gadopentetate dimeglumine shows homogeneous enhancement of the mass (arrows). **(d)** Photograph shows a round elevated erythematous tumor involving the right lower eyelid. A central superficial ulcer and crust are noted; these represent the typical gross morphology of cutaneous ALCL.

**Figure 14a.** Primary systemic type ALCL in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×200; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of large lymphoid cells (arrows) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of Ki-1 antigen-labeled tissue shows atypical lymphoid cells that react positively and appear brown. **(c)** Anteroposterior chest radiograph shows disseminated nodules involving both lungs (open arrows). Right-sided paratracheal bulging suggestive of lymph node enlargement (solid arrows) and pleural effusions are also seen. **(d)** Chest CT scan (lung window) shows nodular consolidations containing air bronchograms in both lungs (arrows). **(e)** Chest CT scan shows conglomerated interlobar and peribronchial enlarged lymph nodes (arrows). Bilateral pleural effusions are also noted. **(f)** Abdominal CT scan shows multiple enlarged lymph nodes in the mesentery of the left gastric and gastrohepatic area (open arrows). Multiple enhancing nodules suggestive of pleural seeding (solid arrows) and bilateral pleural effusions are also noted.

**Figure 14b.** Primary systemic type ALCL in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×200; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of large lymphoid cells (arrows) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of Ki-1 antigen-labeled tissue shows atypical lymphoid cells that react positively and appear brown. **(c)** Anteroposterior chest radiograph shows disseminated nodules involving both lungs (open arrows). Right-sided paratracheal bulging suggestive of lymph node enlargement (solid arrows) and pleural effusions are also seen. **(d)** Chest CT scan (lung window) shows nodular consolidations containing air bronchograms in both lungs (arrows). **(e)** Chest CT scan shows conglomerated interlobar and peribronchial enlarged lymph nodes (arrows). Bilateral pleural effusions are also noted. **(f)** Abdominal CT scan shows multiple enlarged lymph nodes in the mesentery of the left gastric and gastrohepatic area (open arrows). Multiple enhancing nodules suggestive of pleural seeding (solid arrows) and bilateral pleural effusions are also noted.

**Figure 14c.** Primary systemic type ALCL in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×200; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of large lymphoid cells (arrows) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of Ki-1 antigen-labeled tissue shows atypical lymphoid cells that react positively and appear brown. **(c)** Anteroposterior chest radiograph shows disseminated nodules involving both lungs (open arrows). Right-sided paratracheal bulging suggestive of lymph node enlargement (solid arrows) and pleural effusions are also seen. **(d)** Chest CT scan (lung window) shows nodular consolidations containing air bronchograms in both lungs (arrows). **(e)** Chest CT scan shows conglomerated interlobar and peribronchial enlarged lymph nodes (arrows). Bilateral pleural effusions are also noted. **(f)** Abdominal CT scan shows multiple enlarged lymph nodes in the mesentery of the left gastric and gastrohepatic area (open arrows). Multiple enhancing nodules suggestive of pleural seeding (solid arrows) and bilateral pleural effusions are also noted.

**Figure 14d.** Primary systemic type ALCL in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×200; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of large lymphoid cells (arrows) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of Ki-1 antigen-labeled tissue shows atypical lymphoid cells that react positively and appear brown. **(c)** Anteroposterior chest radiograph shows disseminated nodules involving both lungs (open arrows). Right-sided paratracheal bulging suggestive of lymph node enlargement (solid arrows) and pleural effusions are also seen. **(d)** Chest CT scan (lung window) shows nodular consolidations containing air bronchograms in both lungs (arrows). **(e)** Chest CT scan shows conglomerated interlobar and peribronchial enlarged lymph nodes (arrows). Bilateral pleural effusions are also noted. **(f)** Abdominal CT scan shows multiple enlarged lymph nodes in the mesentery of the left gastric and gastrohepatic area (open arrows). Multiple enhancing nodules suggestive of pleural seeding (solid arrows) and bilateral pleural effusions are also noted.

**Figure 14e.** Primary systemic type ALCL in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×200; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of large lymphoid cells (arrows) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of Ki-1 antigen-labeled tissue shows atypical lymphoid cells that react positively and appear brown. **(c)** Anteroposterior chest radiograph shows disseminated nodules involving both lungs (open arrows). Right-sided paratracheal bulging suggestive of lymph node enlargement (solid arrows) and pleural effusions are also seen. **(d)** Chest CT scan (lung window) shows nodular consolidations containing air bronchograms in both lungs (arrows). **(e)** Chest CT scan shows conglomerated interlobar and peribronchial enlarged lymph nodes (arrows). Bilateral pleural effusions are also noted. **(f)** Abdominal CT scan shows multiple enlarged lymph nodes in the mesentery of the left gastric and gastrohepatic area (open arrows). Multiple enhancing nodules suggestive of pleural seeding (solid arrows) and bilateral pleural effusions are also noted.

**Figure 14f.** Primary systemic type ALCL in a 12-year-old girl. **(a)** Photomicrograph (original magnification, ×200; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of large lymphoid cells (arrows) with pleomorphic nuclei, prominent nucleoli, and abundant cytoplasm. **(b)** Photomicrograph (original magnification, ×200; immunohistochemical stain on paraffin-embedded material) of Ki-1 antigen-labeled tissue shows atypical lymphoid cells that react positively and appear brown. **(c)** Anteroposterior chest radiograph shows disseminated nodules involving both lungs (open arrows). Right-sided paratracheal bulging suggestive of lymph node enlargement (solid arrows) and pleural effusions are also seen. **(d)** Chest CT scan (lung window) shows nodular consolidations containing air bronchograms in both lungs (arrows). **(e)** Chest CT scan shows conglomerated interlobar and peribronchial enlarged lymph nodes (arrows). Bilateral pleural effusions are also noted. **(f)** Abdominal CT scan shows multiple enlarged lymph nodes in the mesentery of the left gastric and gastrohepatic area (open arrows). Multiple enhancing nodules suggestive of pleural seeding (solid arrows) and bilateral pleural effusions are also noted.

**Figure 15a.** Angioimmunoblastic T-cell lymphoma in an 18-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of lymphoid cells and prominent vascular proliferation (arrows). **(b)** High-power photomicrograph (original magnification, ×200; H-E stain) shows lymphoid cells admixed with immunoblasts (arrowhead) and plasma cells (straight arrows). Vascular proliferation (curved arrow) is also noted. The term *angioimmunoblastic* in the name of this condition is due to the vascular proliferation and admixed immunoblasts. **(c)** Contrast-enhanced chest CT scan shows multiple enlarged lymph nodes (arrows) in the prevascular, right lower paratracheal, and axillary areas. Bilateral pleural effusions are also noted. **(d)** Abdominal CT scan shows enlargement of the liver and spleen. Multiple enlarged lymph nodes are seen in the hepatic hilum, splenic hilum, and retrocrural area (arrows). **(e)** CT scan shows multiple enlarged lymph nodes in the mesentery and retroperitoneal area (arrows) and ascites. Multiple enlarged mesenteric lymph nodes and mesenteric nodules are suggestive of mesenteric lymphomatosis.

**Figure 15b.** Angioimmunoblastic T-cell lymphoma in an 18-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of lymphoid cells and prominent vascular proliferation (arrows). **(b)** High-power photomicrograph (original magnification, ×200; H-E stain) shows lymphoid cells admixed with immunoblasts (arrowhead) and plasma cells (straight arrows). Vascular proliferation (curved arrow) is also noted. The term *angioimmunoblastic* in the name of this condition is due to the vascular proliferation and admixed immunoblasts. **(c)** Contrast-enhanced chest CT scan shows multiple enlarged lymph nodes (arrows) in the prevascular, right lower paratracheal, and axillary areas. Bilateral pleural effusions are also noted. **(d)** Abdominal CT scan shows enlargement of the liver and spleen. Multiple enlarged lymph nodes are seen in the hepatic hilum, splenic hilum, and retrocrural area (arrows). **(e)** CT scan shows multiple enlarged lymph nodes in the mesentery and retroperitoneal area (arrows) and ascites. Multiple enlarged mesenteric lymph nodes and mesenteric nodules are suggestive of mesenteric lymphomatosis.

**Figure 15c.** Angioimmunoblastic T-cell lymphoma in an 18-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of lymphoid cells and prominent vascular proliferation (arrows). **(b)** High-power photomicrograph (original magnification, ×200; H-E stain) shows lymphoid cells admixed with immunoblasts (arrowhead) and plasma cells (straight arrows). Vascular proliferation (curved arrow) is also noted. The term *angioimmunoblastic* in the name of this condition is due to the vascular proliferation and admixed immunoblasts. **(c)** Contrast-enhanced chest CT scan shows multiple enlarged lymph nodes (arrows) in the prevascular, right lower paratracheal, and axillary areas. Bilateral pleural effusions are also noted. **(d)** Abdominal CT scan shows enlargement of the liver and spleen. Multiple enlarged lymph nodes are seen in the hepatic hilum, splenic hilum, and retrocrural area (arrows). **(e)** CT scan shows multiple enlarged lymph nodes in the mesentery and retroperitoneal area (arrows) and ascites. Multiple enlarged mesenteric lymph nodes and mesenteric nodules are suggestive of mesenteric lymphomatosis.

**Figure 15d.** Angioimmunoblastic T-cell lymphoma in an 18-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of lymphoid cells and prominent vascular proliferation (arrows). **(b)** High-power photomicrograph (original magnification, ×200; H-E stain) shows lymphoid cells admixed with immunoblasts (arrowhead) and plasma cells (straight arrows). Vascular proliferation (curved arrow) is also noted. The term *angioimmunoblastic* in the name of this condition is due to the vascular proliferation and admixed immunoblasts. **(c)** Contrast-enhanced chest CT scan shows multiple enlarged lymph nodes (arrows) in the prevascular, right lower paratracheal, and axillary areas. Bilateral pleural effusions are also noted. **(d)** Abdominal CT scan shows enlargement of the liver and spleen. Multiple enlarged lymph nodes are seen in the hepatic hilum, splenic hilum, and retrocrural area (arrows). **(e)** CT scan shows multiple enlarged lymph nodes in the mesentery and retroperitoneal area (arrows) and ascites. Multiple enlarged mesenteric lymph nodes and mesenteric nodules are suggestive of mesenteric lymphomatosis.

**Figure 15e.** Angioimmunoblastic T-cell lymphoma in an 18-year-old woman. **(a)** Photomicrograph (original magnification, ×100; H-E stain) of a cervical lymph node biopsy specimen shows diffuse proliferation of lymphoid cells and prominent vascular proliferation (arrows). **(b)** High-power photomicrograph (original magnification, ×200; H-E stain) shows lymphoid cells admixed with immunoblasts (arrowhead) and plasma cells (straight arrows). Vascular proliferation (curved arrow) is also noted. The term *angioimmunoblastic* in the name of this condition is due to the vascular proliferation and admixed immunoblasts. **(c)** Contrast-enhanced chest CT scan shows multiple enlarged lymph nodes (arrows) in the prevascular, right lower paratracheal, and axillary areas. Bilateral pleural effusions are also noted. **(d)** Abdominal CT scan shows enlargement of the liver and spleen. Multiple enlarged lymph nodes are seen in the hepatic hilum, splenic hilum, and retrocrural area (arrows). **(e)** CT scan shows multiple enlarged lymph nodes in the mesentery and retroperitoneal area (arrows) and ascites. Multiple enlarged mesenteric lymph nodes and mesenteric nodules are suggestive of mesenteric lymphomatosis.

**TABLE 1. WHO Classification of T-Cell and NK-Cell Neoplasms**

Sources.—References 1–5.

Note.—NK = natural killer.

**TABLE 2. International Prognostic Index for Non-Hodgkin Lymphoma**

Source.—Reference 10.

Note.—ECOG = Eastern Cooperative Oncology Group.

**TABLE 3. Clinicopathologic Entities of PTCL and Common Primary Involved Organs**

Abbreviations: H-E = hematoxylin-eosin, NK = natural killer, PTCL = peripheral T-cell lymphoma

See the commentary by Levy and Koeller following this article.

∗∗. Multiple body systems

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Published in print: Jan 2003

Vol. 23, No. 1

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