[539] The Histomorphologic Spectrum of Primary Cutaneous Diffuse Large B-Cell Lymphoma (DLBCL), “Leg Type” and “Other” Category: A Histopathologic and Immunohistochemical Study of 79 Cases

D Stockman, S Suster, D Kacerovska, D Kazakov, JA Plaza. Medical College of Wisconsin, Milwaukee, WI; Charles University Medical Faculty Hospital Alej Svobody 80, Pilsen, Czech Republic

Background: Primary cutaneous diffuse large B-cell lymphomas have been historically matter of debate in the literature. Recently, in 2005 the WHO-EORTC classified cutaneous B-cell lymphomas into the following main 3 groups: primary cutaneous marginal zone B-cell lymphoma, primary cutaneous follicle center cell lymphoma, and primary cutaneous diffuse large B-cell lymphoma, leg type. In the WHO-EORTC classification the term PCLBCL other is used in rare cases of PCLBCL that do not belong to the leg type group or the group of PCFCL. In this study we assessed retrospectively the morphologic, immunophenotypic, and the clinical features of 79 cases of PCDLBCLs including the leg type and the other category in order to better categorize the histologic and clinical spectrum of this unusual neoplasm.
Design: 79 cases were analyzed (M: F = 37 : 42, range age: 34 to 94). 53 cases were classified as leg type and 26 cases were classified as other by using the WHO-EORTC classification. Of the 53 cases classifies as leg type 33 were Females and 20 were Males; of the 26 cases of other NOS type, 9 were Females and 17 were Males.
Results: PCDLBCL leg type was characterized by an older age on onset (mean 64), female predominance, predilection for the leg (58.4%), high proportion of bcl-2 expression and extracutaneous dissemination. The PCDLBCL NOS type was characterized also by advanced age of onset (mean 58), male predominance, and predilection to head and neck area. Most of the cases showed the classic morphologic appearance of PCDLBCL, but cases mimicking Burkitt lymphoma (starry-sky pattern), subcutaneous t-cell lymphoma, NK lymphoma, mycosis fungoides (epidermotropism), low-grade B-cell lymphomas, epithelial malignancies, Merkel cell carcinoma, etc were encountered in this series. Immunohistochemical stains plus careful histologic examination helped to establish the correct diagnosis.
Conclusions: The histologic diagnosis of PCDLBCL poses little diagnostic difficulty; however, some cases may adopt unusual or unfamiliar appearances mimicking other lymphoproliferative disorders. We believe the differential diagnosis of PCDLBCL sometimes can be broad and difficult to define both clinically and histologically. To the best of our knowledge this is the largest series of PCDLBCL reported in the literature.
Category: Dermatopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 95, Wednesday Afternoon

 

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