Characteristics of primary cutaneous lymphoma according to WHO‐EORTC classification in Korea

Background.  Primary cutaneous lymphoma (PCL) is an extranodal non‐Hodgkin lymphoma with primary involvement of the skin. Epidemiological data on PCLs according to the World Health Organization/European Organization for Research and Treatment of Cancer classification (WHO‐EORTC) has not been investigated in Korea to date. Aim.  To evaluate the demographic characteristics, clinical and histological features, and survival data of patients with PCL according to the WHO‐EORTC classification. Methods.  In total, 93 patients with PCL were retrospectively identified from an extensive review of medical records over a 16‐year period. Results. The tumours found included primary cutaneous CD30+ lymphoproliferative disorders, extranodal natural killer/T‐cell lymphoma and primary cutaneous diffuse large B‐cell lymphoma. We found that 81.6% of the patients had primary cutaneous T‐cell and natural killer‐cell lymphoma, and 16.2% had primary cutaneous B‐cell lymphoma, with 2.2% having precursor haematological neoplasms. The median age was 52 years (range 3–95) and the male : female ratio was 1 : 1.16. The 5‐year survival rate was 92.5%. Conclusions.  The incidence rates of many PCL subtypes in Koreans differ from those of other countries.     

Cutaneous lymphomas other than mycosis fungoides in Singapore: a clinicopathological analysis using recent classification systems

BACKGROUND: Cutaneous lymphomas other than mycosis fungoides (MF) are a heterogeneous group with wide variations in clinical presentation, biological behaviour and prognosis. New classification systems have been designed or proposed in recent years, with well-defined disease entities and emphasis on the importance of site. OBJECTIVES: This study aims to analyse a series of non-MF lymphomas in an institution-based dermatological setting in Singapore, based on the European Organization for Research and Treatment of Cancer (EORTC) classification and the World Health Organization (WHO) classification. A secondary objective is to highlight the clinical utility of both classification systems. PATIENTS AND METHODS: Forty cases diagnosed over a 12-year period were examined by immunohistochemistry with antibodies targeting CD3, CD4, CD5, CD8, CD20, CD30, CD43, CD45RO, CD56 and CD68 in paraffin-embedded specimens. The immunohistological diagnosis was correlated with the clinical presentation and staging investigations for the final diagnosis and the course of disease recorded. RESULTS: Non-MF T-cell lymphomas presenting in the skin comprised 31 cases (78%) and were 3(1/2) times more common than B-cell lymphomas, which comprised nine cases (22%). The common subtypes were lymphomatoid papulosis, CD30+ large cell cutaneous T-cell lymphoma and subcutaneous panniculitis-like T-cell lymphoma. The commonly ascribed B-cell pattern with infiltrates in the mid and deep dermis and perivascular spaces was seen in 60% of T-cell lymphomas. Overall, there were equal numbers of primary cutaneous T-cell lymphomas and those due to concurrent or secondary cutaneous lymphoma. Five of six cases of subcutaneous panniculitis-like T-cell lymphoma had concurrent cutaneous and systemic involvement and their median survival was 7 months. CONCLUSIONS: The predominance of cutaneous T-cell lymphomas in this case series closely matched that reported from east Asia; cutaneous B-cell lymphomas are much less common than in Europe. The EORTC classification, which is designed only for primary cutaneous lymphomas, should be used in conjunction with the WHO classification because of the high prevalence of cutaneous lymphomas as the secondary site of disease from systemic lymphoma. In addition, subcutaneous panniculitis-like T-cell lymphoma is a primary cutaneous lymphoma where systemic involvement is common at initial presentation. We propose full immunophenotyping and complete clinical evaluation with staging investigations for all patients presenting with cutaneous lymphomas other than MF.     

Incidence and ten-year follow-up of primary cutaneous lymphomas: a single-centre cohort study

Background

Primary cutaneous lymphomas (PCLs) are a rare group of extranodal non-Hodgkin lymphomas, and epidemiological data in Mediterranean countries are scarce.

Objective

To investigate the incidence and characteristics of PCL in a single tertiary referral centre in Italy.

Materials & methods

A total of 141 PCL patients, seen over a 10-year follow-up period, were investigated.

Results

Incidence rate of PCL was 0.8 cases/100,000 person years. T-cell lymphoma represented 78.7% of all cases, the majority being early mycosis fungoides (MF) (64%; median age: 66 years), followed by lymphomatoid papulosis (LyP) (19%; median: age 48 years), and others (median age: 72 years), including eight cases of anaplastic large CD30+ T-cell lymphoma, four CD4+ smallmedium pleomorphic T-cell lymphoproliferative disorder, four Sézary syndrome, one subcutaneous panniculitis-like T-cell lymphoma, one extranodal NK/T-cell lymphoma nasal-type, and one angioimmunoblastic T-cell lymphoma. B-cell lymphoma accounted for 21.3% of PCL, with 20 cases of cutaneous follicular centre B-cell (median age: 63 years), four primary cutaneous marginal zone, three primary cutaneous diffuse large B-cell, and three leg-type lymphoma. Complete remission within the first year after diagnosis occurred in 70.4% of MF, 61.9% of LyP, 78.9% of other T-cell lymphoma, and 93.1% of B-cell lymphoma cases. Based on a Cox proportional hazard regression model, age, gender, stage, and lactate dehydrogenase and β2-microglobulin blood levels did not predict clinical remission ofMFor LyP.

Conclusions

The incidence and characteristics of PCL in Italy are similar to those in other European countries. PCLs may be diagnosed at very early stages with good prognosis.

     

Cutaneous lymphoma in Japan, 2012–2017: A nationwide study

BackgroundThe types of cutaneous lymphoma (CL) and their incidences can vary among geographic areas or ethnic groups.ObjectiveThis study aimed to investigate the incidence of various CL types in Japan using epidemiological data from a nationwide registration system for CL.MethodsA questionnaire was sent to participating hospitals, all of which had been approved to conduct residency programs for board-certified dermatologists by the Japanese Dermatological Association. Data from patients newly diagnosed with CL were collected electronically.ResultsBetween 2012 and 2017, 2547 new patients with CL from the dermatological institutes were registered. In total, 2090 patients had primary CL and 453 had secondary CL. Those with primary CL included 1609 (77.0 %) patients with mature T- and natural killer (NK)-cell neoplasms, 442 (21.1 %) with B-cell neoplasms, and 39 (1.9 %) with blastic plasmacytoid dendritic cell neoplasms. Mycosis fungoides (MF) was the most common CL subtype in the present study (1003 patients, 48.0 %), and 72.4 % of MF patients had early-stage disease, similar to observations in previous studies on other cohorts. Primary cutaneous CD30+ T-cell lymphoproliferative disorders and adult T-cell leukemia/lymphoma were the second and third most common subtypes, respectively.ConclusionCompared to that in our previous cohort (2007–2011), the number of registered T- and NK-cell CL cases decreased, whereas that of B-cell CL cases increased from 44.8–73.7 patients/year. These results provide insight into CL trends within the Japanese population, which might contribute to a better understanding of the disease.     

Characteristics of cutaneous lymphomas in Korea

The clinicopathologic characteristics of malignant lymphomas vary according to geography. The aim of this study was to determine the relative frequency of cutaneous lymphomas and to examine the clinical relevance of the WHO classification in Korean cases of cutaneous lymphoma. The Korean Dermatopathology Research Group conducted a clinicopathologic review of a nationwide collection of 80 cutaneous lymphomas, diagnosed at 23 institutes over a recent 3-year period. The clinical records, haematoxylin & eosin-stained slides and immunohistochemical stains from 80 patients with malignant lymphomas of the skin were reviewed. In our study, the most frequent cutaneous lymphoma was mycosis fungoides. Compared with Western countries, Korea had higher rates of NK/T cell lymphoma and subcutaneous panniculitis-like T-cell lymphoma and a much lower rate of B-cell lymphoma. The occurrence rates for various subtypes of malignant lymphoma in Korea are distinct from those in Western countries. The EORTC classification is not fully appropriate in dealing with Korean cases of cutaneous lymphoma, because NK/T cell lymphoma is not included in the EORTC classification for cutaneous lymphoma.     

18F-fluorodeoxyglucose-positron emission tomography in evaluation of primary cutaneous lymphoma

BACKGROUND: The diagnosis of primary cutaneous lymphoma (PCL) is currently based on clinical and histological findings and/or relatively invasive procedures such as bone marrow and fine-needle lymph node biopsies. Although computed tomography (CT) is a noninvasive imaging modality that is widely used for staging in patients with lymphoma, it cannot provide information about malignant cutaneous lesions. OBJECTIVES: To investigate the usefulness of (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) in the management of PCL. METHODS: We retrospectively analysed 31 FDG-PET studies in 19 patients with PCL [15 T-cell non-Hodgkin lymphoma (NHL) and four B-cell NHL]. There were 10 men and nine women (age range 23-84 years, mean +/- SD 54 +/- 16). Eleven FDG-PET studies were performed for initial staging and 20 FDG-PET studies were performed for restaging following therapy. Results of FDG-PET were compared with those of CT. Clinical parameters and/or biopsy results of lesions served as reference for the accuracy of PET and CT in evaluating local and metastatic lesions. RESULTS: For the initial staging, FDG-PET had a sensitivity of 82% for the evaluation of local disease and 80% for the detection of distant metastasis. The corresponding values for CT were 55% and 100%, respectively. For restaging of cutaneous lymphoma, FDG-PET had a sensitivity of 86% and specificity of 92% for local recurrence/residual disease and a sensitivity of 100% and specificity of 100% for distant metastasis. The corresponding values for CT were 50% and 83% for local recurrence/residual disease and 100% and 67% for distant metastasis. CONCLUSIONS: FDG-PET has a potential value for initial staging and restaging following therapy in patients with PCL. FDG-PET has higher diagnostic value than CT in the detection both of local disease and distant metastasis.     

Polymerase chain reaction analysis of immunoglobulin gene rearrangement in cutaneous lymphoid hyperplasias. French Study Group for Cutaneous Lymphomas

The differential diagnosis of cutaneous lymphoid hyperplasia and B-cell lymphoma may be difficult. Whether the detection of clonal immunoglobulin gene rearrangement in the cutaneous lesion is predictive of a malignant outcome remains controversial. We therefore studied cases of cutaneous lymphoid hyperplasia by polymerase chain reaction analysis. DESIGN: Retrospective study of patients seen between 1988 and 1996. SETTING: Two dermatology university departments. PATIENTS: Twenty-four patients with cutaneous lymphoid hyperplasias were included according to clinical, histopathological, and immunophenotypic criteria. MAIN OUTCOME MEASURES: Clinical, histopathological, and laboratory findings. RESULTS: There were 13 men and 11 women (mean age, 49 years) who presented with erythematous or violaceous papules or nodules. The lesions were unique in 13 cases and multiple in 11 cases. All patients had immunochemical evidence of a mixed T- and B-cell infiltrate with polytypic B cells. Polyclonality was demonstrated in 23 patients, whereas a dominant B-cell clone was detected in 1 patient. No lymphoma developed during the follow-up (median, 4 years). In the same period, we studied 53 cases of B-cell lymphomas. Thirty-five (66%) of the 53 cases had a detectable clonal immunoglobulin gene rearrangement. CONCLUSIONS: In the majority of our cases, polyclonality demonstrated by polymerase chain reaction analysis was in accordance with the diagnosis of cutaneous lymphoid hyperplasia. In 1 of the 24 patients, the presence of a B-cell clone could be evidenced. This fact did not modify the treatment as there were no histological or immunophenotypic signs suggestive of a lymphoma.     

Survival data for 299 patients with primary cutaneous lymphomas: a monocentre study

The aim of this study was retrospectively to assess the validity of the 2005 WHO-EORTC classification for primary cutaneous lymphomas (PCL) in a large cohort of patients of a single German skin cancer unit. All patients with PCLs consecutively visiting our hospital between January 1980 and December 2005 were included in a retrospective monocentre study, analysing their histological and clinical data. A total of 312 patients fulfilled the inclusion criteria for PCL. In 299 patients clinical information and paraffin material were sufficient for detailed classification. Of the 299 patients, 63% expressed a T-cell and 37% a B-cell phenotype. Mycosis fungoides was the entity with the highest frequency (30.9%), followed by primary cutaneous follicle centre lymphomas (16.9%) and lymphomatoid papulosis (15.9%). The mean follow-up period was 38.4 months. Five-year disease-specific survival was 80.5% for mycosis fungoides, 92.5% in primary cutaneous anaplastic large cell lymphoma, 100% in lymphomatoid papulosis, 98.1% in primary cutaneous follicle center lymphoma, 100% in primary cutaneous marginal zone lymphoma and 63.2% in diffuse large B-cell lymphoma, leg type. Our data are in line with the data collected by the WHO-EORTC. This is further evidence for the reliability of the WHO-EORTC classification and staging system.     

Clinicopathologic reassessment of non-mycosis fungoides primary cutaneous lymphomas during 17 years

BACKGROUND: New classification systems have recently been proposed for primary cutaneous lymphomas (PCLs). The aim of our study was to evaluate the applicability and significance of the new classification systems to the diagnosis and management of non-mycosis fungoides (non-MF) PCL. METHODS: Immunohistochemical restaining, histological reclassification, and clinical follow-up of all new non-MF PCL cases during 17 consecutive years were performed. The histological reclassification was performed according to the Revised European-American Lymphoma (REAL) classification, except for lymphomatoid papulosis (Lyp), which was included as an indolent lymphoma, according to the European Organization for the Research and Treatment of Cancer (EORTC) classification. RESULTS: During the period 1983-99, 251 new PCL cases were seen, 213 (85%) of which were MF and Sézary syndrome (eight cases), and 38 (15%) of which were non-MF. Of the latter, 20 (53%) were B-cell lymphomas, including eight (40%) follicle center lymphoma, follicular (FCLF), eight (40%) marginal zone lymphoma (MZL), two (10%) diffuse large cell lymphoma, and two (10%) unclassifiable cases. Most or all of the lesions did not stain for CD10, CD43, and bcl-2 protein, and immunostaining for kappa and lambda immunoglobulin light chain restriction was much more useful diagnostically in MZL. Of the 18 primary non-MF cutaneous T-cell lymphomas, 13 (72%) were Lyp, all of which were type A, four (22%) were CD30+ anaplastic large cell lymphoma, and one (6%) was natural killer (NK)/T-cell lymphoma. Except for the NK/T-cell lymphoma, all the other non-MF PCLs had an indolent course. CONCLUSIONS: A minority of the routinely diagnosed PCLs are non-MF, equally divided between B- and T-cell lymphomas. The REAL classification is applicable to the majority, although it does not include entities such as Lyp; the clinical correlations are not as obvious because most of the non-MF PCLs tend to have a relatively indolent course.     

Non-Hodgkin lymphoma of the skin excluding mycosis fungoides and cutaneous involvement of adult T-cell leukemia/lymphoma*

Forty-nine cases of cutaneous malignant lymphoma were reviewed in order to analyze the clinicopathological features of these neoplasms. Excluding 13 cases of mycosis fungoides and 4 cases of cutaneous involvement of proven adult T-cell lymphoma/leukemia, the remaining 32 cases were further classified according to their pathological and clinical features. There were 12 primary cutaneous lymphomas, 15 cases of secondary cutaneous involvement of systemic lymphoma, and 5 cases of concurrent skin and lymph node involvement. Histologically, large cell lymphoma predominated in both primary and secondary cutaneous lymphomas. Immunohistochemical study using monoclonal antibodies reactive with B- and T-cells in paraffin sections revealed the cellular lineage in 30 cases. Nineteen cases were of T-cell origin and 11 cases were of B-cell derivation. The prognosis of these patients was rather poor; 25 patients died within 5 years. The predominance of T-cell lymphoma contrasts with a higher frequency of cutaneous B-cell lymphoma in Western countries. As the clinicopathological features of cutaneous lymphomas are diverse, it is suggested that cutaneous lymphomas should be classified and studied in a similar way to their nodal counterparts.     

Cutaneous B-cell lymphoma

The various morphologic and functional subtypes of nodal B-cell lymphomas can also be found in the skin. These reflect the various steps of lymphocyte differentiation including maturation from the pre-B lymphocyte to the well-differentiated B2 lymphocyte or plasma cell in the peripheral blood. The subtypes of cutaneous B-cell lymphomas have been discussed (Kiel classification); the percentages indicate the frequencies of the subtypes among a total of 736 cutaneous lymphomas of both T-cell and B-cell origin: Lymphocytic lymphoma (7 per cent). Immunoglobulin-producing lymphomas, including the rate plasmacytoma of the skin, lymphoplasmacytoid immunocytoma, which represents the largest group of cutaneous B-cell lymphoma (12 per cent), and immunoblastic lymphoma, which is the most aggressive form in this group (8 per cent). Cutaneous B-cell lymphoma arising from or related to follicular center cells, including centrocytic lymphoma (7 per cent), mantle-cell lymphoma, centroblastic/centrocytic lymphoma (6 per cent), the highly malignant centroblastic lymphoma (4 per cent), and lymphoblastic lymphoma, Burkitt type. The Ann Arbor staging system is not applicable to cutaneous B-cell lymphoma; therefore, a TNM staging system has been proposed. The diagnosis of cutaneous B-cell lymphoma is based primarily on cytomorphologic features. Differentiation of cutaneous B-cell lymphoma from pseudolymphoma of the skin cannot be based on a single criterion; a spectrum of characteristic features must be evaluated. Analysis of the infiltrating cells in cutaneous B-cell lymphoma using monoclonal antibodies demonstrates that the proliferation of the neoplastic clone is accompanied by a mixture of accessory cells of various origins, including T cells, macrophages, and dendritic reticulum cells. As in nodal B-cell lymphomas, several factors may be involved in the generation of cutaneous B-cell lymphoma, including persistent antigenic stimulation and loss of regulatory mechanisms for lymphocyte proliferation and differentiation in conjunction with environmental and other factors.     

Retrospective analysis of 133 patients with cutaneous lymphomas from a single Japanese medical center between 1995 and 2008

In 2008, a revised World Health Organization (WHO) system of hematological neoplasm classification was promulgated. Between January 1995 and December 2008, 133 new patients with cutaneous lymphomas were seen at the dermatology clinic of Okayama University Hospital. All patients were re-classified according to the revised WHO system. The incidence rates were analyzed and the survival was estimated. Of 133 patients, 106 (79.7%) had primary cutaneous lymphomas (PCLs) and 27 (20.3%) were skin invasion from extracutaneous origin of systemic lymphoma. Compared with several reports from western countries, "mature T-cell and NK-cell neoplasms" was frequent in this study (87% vs. 77 or 72%) because of the occurrence of adult T-cell leukemia/lymphoma (ATLL) and "extranodal NK/T cell lymphoma, nasal type", with less frequent occurrence of "mature B-cell neoplasms" (13% vs. 23 or 28%). Estimated survival of patients with mycosis fungoides was favorable (5-year survival rate 90.6%), but that of the patients with primary cutaneous anaplastic large cell lymphoma (C-ALCL) was extremely less favorable than previously reported (5-year survival rate of 47.4%).     

The applicability of the new WHO-EORTC classification of primary cutaneous lymphomas to a single referral center

Recent years have witnessed differences between the World Health Organization (WHO) and the European Organization for Research and Treatment of Cancer (EORTC) classification systems of primary cutaneous lymphomas (PCLs). Recently, a joint WHO-EORTC classification system for PCLs has been reached. This study was performed to assess the applicability of this new classification to a single referral center. All new PCL cases, excluding mycosis fungoides and Sezary syndrome, who were referred from 1999 to 2005 were included. The histological, immunohistochemical stainings and molecular studies were reviewed, and additional stains were performed as needed. The cases were then reclassified according to the WHO-EORTC classifications. The clinical files were also studied, and the patients were followed up clinically. There were 43 new non-mycosis fungoides/Sezary syndrome PCLs, including 29 B-cell lymphomas of which 14 were follicle center lymphoma, 10 marginal zone lymphoma, 4 diffuse large-B-cell lymphoma, leg type, and 1 diffuse large-B-cell lymphoma, other. The 14 T-cell lymphomas included 5 cases of lymphomatoid papulosis, 2 CD30+ anaplastic large-cell lymphomas, 1 NK/T-cell lymphoma, and 6 peripheral T-cell lymphomas, unspecified. Of the 6 "unspecified" T-cell lymphomas, 3 were CD4+ small/medium-sized pleomorphic T-cell lymphoma, which is considered currently a provisional entity under the unspecified T-cell category. The remaining 3 cases could not be classified beyond the unspecified T-cell category, of which 2 cases had an aggressive course. The new WHO-EORTC classification is applicable to most non-mycosis fungoides/Sezary syndrome PCL cases, especially the B-cell lymphomas. However, there is still a substantial subset of T-cell PCLs which cannot be classified beyond the unspecified peripheral T-cell category, some of which may have an aggressive course.     

42例原发性皮肤恶性淋巴瘤分类的研究

目的 了解原发性皮肤恶性淋巴瘤（ＰＣＭＬ）的类型分布及临床病理特点。方法 主要依据Ｗｉｌｌｅｍｚｅ等１９９４年提出的ＰＣＭＬ分类标准对４２全ＰＣＭＬ进行分类研究。结果 ①在ＰＣＭＬ中,皮肤Ｔ细胞淋巴瘤（ＣＴＣＬ）多见（６９．０％）,其中蕈样内芽肿（ＭＦ）占７．２％。皮肤Ｂ细胞淋巴瘤（ＣＢＣＬ）较少见（３１．０％）。②ＰＣＭＬ中男女之比为２：１,中位发病年龄３７岁,ＣＴＣＬ的中位发病年龄小于ＣＢＣＬ（Ｐ〈０．０１）,高度恶性ＰＣＭＬ的中位发病年龄小于低度恶性ＰＣＭＬ（Ｐ〈０．０１）。③临床上,ＭＦ可表现为红斑、斑块等非特异性皮损,而其它各类皮损均表现为无症状性皮肤结节、肿块。结论 ＰＣＭＬ各类型具有不同的临床病理特点。     

Primary cutaneous diffuse large B-cell lymphoma, leg type: clinicopathologic features and prognostic analysis in 60 cases

OBJECTIVES: To describe clinicopathologic features and to identify prognostic factors in a large series of primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL LT), as defined in the recent World Health Organization-European Organization for Research and Treatment of Cancer classification of cutaneous lymphomas. DESIGN: Retrospective multicenter study from the French Study Group on Cutaneous Lymphomas. SETTING: Nineteen departments of dermatology in 10 regions of France. PATIENTS: Sixty patients with a PCLBCL LT included in the registry of the French Study Group on Cutaneous Lymphomas. MAIN OUTCOME MEASURES: Age, sex, outcome, therapy, B symptoms, cutaneous extent, number of lesions, location (leg vs nonleg), serum lactate dehydrogenase level, and MUM-1 and Bcl-2 expression were recorded. Disease-specific survival was used as the main end point. Prognostic factors were identified using a Cox proportional hazards model. RESULTS: Primary cutaneous diffuse large B-cell lymphoma, leg type is characterized by a predilection for the leg (72%), a high proportion of Bcl-2 expression (85%), an advanced age at onset (mean age, 76 years), and frequent relapses and extracutaneous dissemination. The overall 5-year disease-specific survival rate was 41%. Location on the leg and multiple skin lesions were predictive of death in multivariate analysis. Although no variable related to therapy was significantly associated with survival, patients recently treated with combinations of anthracycline-containing chemotherapies and rituximab had a more favorable short-term outcome. CONCLUSIONS: Primary cutaneous diffuse large B-cell lymphoma, leg type is a distinct entity with a poor prognosis, particularly in patients with multiple tumors on the legs. Despite the advanced age of many patients, the prognosis could be improved with combinations of anthracycline-containing chemotherapies and rituximab.     

Diagnostic principles and new developments in primary cutaneous B-cell lymphomas

The most common subtypes of primary cutaneous B-cell lymphomas are marginal zone B-cell lymphoma/immunocytoma, follicle center cell lymphoma, and large B-cell lymphoma of the leg. Precise classification (European Organization for Research and Treatment of Cancer (EORTC) scheme) can be achieved only after a complete synthesis of clinical, histopathological, immunophenotypic, and molecular features. It is extremely important to emphasize that primary cutaneous B-cell lymphomas differ significantly from their nodal counterparts and are frequently characterized by an excellent prognosis. Awareness of this special clinical behavior should prevent the application of unnecessarily aggressive treatment protocols. Future definitions of primary cutaneous B-cell lymphomas will be based on their etiology and pathogenesis and especially on their molecular features. Some important areas are presented where exciting findings have been detected.     

The histopathologic classification of cutaneous lymphomas

A classification of malignant lymphomas has been formulated to identify distinct clinical groups of patients for future therapeutic trials. The unifying concept of primary cutaneous lymphomas as of either T- or B-cell origin does not conflict with the Working Formulation but encompasses its categories. This classification requires immunologic data in addition to morphologic assessment for accurate evaluation. Cytomorphologic subdivision of the cutaneous T-cell lymphomas does not have the same clinical significance as for the cutaneous B-cell lymphomas. However, the pattern of skin involvement in cutaneous T-cell lymphoma (epidermotropic versus nonepidermotropic) does appear to be important clinically and should be included in future classifications.     

Cutaneous natural killer/T-cell lymphoma

Lymphomas are classified as either Hodgkin's or non-Hodgkin's. The 2 subtypes of non-Hodgkin's lymphoma that can present primarily in the skin are cutaneous T-cell lymphoma and cutaneous B-cell lymphoma, both of which tend to be low-grade malignant neoplasms. Recently another distinct subtype of lymphoma was discovered, the natural killer (NK)/T-cell lymphoma, which can involve the skin in a primary or secondary fashion. The NK/T-cell subtype of lymphoma is characterized by the expression of the NK-cell antigen CD56. These CD56(+) lymphomas are further subdivided into nasal NK/T-cell lymphomas that commonly present as midfacial destructive disease and non-nasal NK/T-cell lymphomas that often arise in extranodal locations, including the skin. We report a case of aggressive NK-cell leukemia/lymphoma with numerous secondary cutaneous lesions and review the clinical and histopathologic spectrum of non-nasal CD56(+) lymphomas, with an emphasis on the dermatologic findings.     

The protean spectrum of non-Hodgkin lymphomas with prominent involvement of subcutaneous fat

BACKGROUND: Subcutaneous T-cell lymphoma (STCL) represents a controversial entity and a confused concept in the field of cutaneous T-cell lymphomas (CTCLs). Recently, alpha/beta+/CD8+ STCL has been recognized by the new World Health Organization (WHO)-European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphomas as a distinct entity in the group of CTCLs. OBSERVATIONS: We reviewed a series of 53 biopsies from 26 patients (F : M = 19:7; median age: 48; range 18-87) of cutaneous B- and T-cell lymphomas characterized by prominent involvement of the subcutaneous tissue. We could classify our cases according to the following seven categories--(i) STCL: n = 16; (ii) extranodal NK/T-cell lymphoma, nasal type: n = 2; (iii) cutaneous gamma/delta T-cell lymphoma: n = 2; (iv) anaplastic CD30+ large T-cell lymphoma: n = 1; (v) diffuse large B-cell lymphoma, secondary cutaneous: n = 3; (vi) lymphoplasmacytic lymphoma, secondary cutaneous: n = 1; (vii) specific cutaneous manifestations of myelogenous leukemia: n = 1. CONCLUSIONS: We demonstrated the protean nature of lymphomas with prominent involvement of the subcutaneous fat tissues. The term STCL should be restricted to a homogeneous group of cases characterized morphologically by an exclusive involvement of subcutaneous tissues, immunohistochemically by a T-cytotoxic alpha/beta phenotype, and biologically by a relatively good prognosis.