[470] Can Primary Cutaneous Follicle Center Lymphomas (PCFCL) Transform/Progress to Primary Cutaneous Diffuse Large B-Cell Lymphomas (PCDLBCL)? An Immunohistochemical Study of 82 Cases.

J Noelle Buonaccorsi, Dmitry Kazakov, Denisa Kacerovska, Suster Saul, Jose A Plaza. Medical College of Wisconsin, Milwaukee; Sikl's Department of Pathology, Charles University Medical Faculty Hospital, Pilsen, Czech Republic

Background: PCFCL is characterized by a proliferation of neoplastic follicles in the skin and has an excellent prognosis with a 5-year survival of over 95%. PCFCL has several distinctive features when compared with nodal follicular lymphomas, as they are frequently negative for BCL2 and only less than 25% of the cases have a BCL2 rearrangement. The risk of transformation of PCFCL to PCDLBCL has not been clearly delineated in the literature. PCDLBCL as defined by WHO system, are composed of large, transformed B cells without follicular architecture. Transformation of systemic/nodal follicular lymphoma into aggressive diffuse large B-cell lymphoma is associated with rapid disease progression and poor prognosis. We studied 82 cases of PCDLBCL utilizing antibodies for follicular dendritic cells (FDCs), CD21 and CD35, to detect networks of FDC's that could indicate possible transformation of preexisting PCFCL to PCDLBCL.
Design: All cases were classified according to the new WHO/EORTC classification of cutaneous B-cell lymphomas. Primary skin involvement was defined as cutaneous lymphoma without nodal and/or visceral involvement after staging procedures. We included only cases that were characterized by diffuse infiltrates of B-cells without a follicular growth pattern. IHC staining was performed in all cases using CD21 and CD35 antibodies by a standard ABC method.
Results: Histologically, all the cases of PCDLBCL exhibited diffuse growth without evidence of a nodular pattern. Immunohistochemical studies were performed in all 82 cases and in 15 cases the presence of a CD21/CD35+ network of FDC's was noted throughout the tumor. Of the 15 cases that showed residual clusters of FDC's the tumors were located in the upper extremities (4 cases), leg (3), face (2), scalp (2), trunk (2), chest (1), and subclavicular area (1).
Conclusions: Systemic follicular lymphoma can transform or progress into DLBCL, which is usually associated with rapid disease progression, refractoriness to treatment and a poor outcome. This phenomenon, when occurring in the skin, has been rarely addressed in the literature. In summary, these findings support that some cases of PCDLBCL may represent transformed PCFCL. It is important to be aware of this phenomenon since the transformation of an indolent cutaneous PCFCL into high-grade lymphoma may be associated with a more aggressive behavior.
Category: Dermatopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 107, Wednesday Afternoon


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