B. Vergier

Abstract We herein present an overview of the upcoming 5 th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4 th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5 th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

The course of mycosis fungoides (MF) is indolent except when transformation to a large T-cell lymphoma occurs. The diagnosis of transformed MF (T-MF) relies on the presence of more than 25% of large cells on biopsy of an MF lesion. We analyzed 45 patients with T-MF recorded by the French Study Group on Cutaneous Lymphomas to better determine clinicopathological features of MF transformation and to analyze their impact on prognosis. Median time from diagnosis of MF to transformation was 6.5 years. Extracutaneous progression was present in 20 patients. Mean survival from transformation to death was 22 months. In univariate analysis, only an extracutaneous progression was associated with a worse prognosis (5-year actuarial survival: 7.8% versus 32%). Neither sex, age, clinical and skin disease stage at transformation, transformation speed, nor percentage of large cells or CD30 expression (14 of 45) had a prognostic value. When performing multivariate analysis, age (at least 60 years), and extracutaneous spreading were found to be associated with a poor prognosis. There was no difference between survival curves of patients with T-MF and with pleomorphic large T-cell CD30- lymphomas. The main diagnostic pitfall was "histiocytic-rich" MF, requiring CD68 staining for the diagnosis of T-MF. Out of 45 patients, 6 presented an histologic transformation before clinical progression, suggesting that an early histopathological diagnosis may be performed by histological follow-up. The prognostic value of such early histopathological diagnosis must be confirmed by prospective studies.

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.

Blastic natural killer (NK) cell lymphoma (also termed CD4+CD56+ hematodermic neoplasm) is a recently described entity, with the first case reported in 1994. It was suggested initially that the disease originates from NK cells. Since 1994, single cases and a few small series have been published. In this review, data from the literature and a series of 30 cases from the French and Dutch study groups on cutaneous lymphomas are discussed. The major clinical, histopathologic, and phenotypic aspects of the disease and diagnostic criteria and data suggesting a plasmacytoid dendritic cell origin for the tumor cells are provided.

Blastic natural killer (NK) cell lymphoma (also termed CD4+CD56+ hematodermic neoplasm) is a recently described entity, with the first case reported in 1994. It was suggested initially that the disease originates from NK cells. Since 1994, single cases and a few small series have been published. In this review, data from the literature and a series of 30 cases from the French and Dutch study groups on cutaneous lymphomas are discussed. The major clinical, histopathologic, and phenotypic aspects of the disease and diagnostic criteria and data suggesting a plasmacytoid dendritic cell origin for the tumor cells are provided.