TRANSFORMATION OF FOLLICULAR LYMPHOMA INTO CD30 LARGE-CELL LYMPHOMA WITH ANAPLASTIC CYTOLOGIC FEATURES

The natural history of follicular lymphoma is to accrue large cells an d become diffuse, resulting in progression/transformation to a higher- grade lymphoma. Histologic transformation occurs in approximately 60% of patients. Most often, follicular lymphomas transform into diffuse l arge cell lymphoma, but transformation to lymphomas classified using t he Working Formulation as diffuse mixed, large cell immunoblastic, or small noncleaved cell also have been reported. Evidence of transformat ion may be found over time in sequential biopsy specimens, or may coex ist in the same biopsy specimen. Here, we describe six cases of follic ular lymphoma, large cell in five cases and mixed in one case, that tr ansformed into a diffuse or sinusoidal CD30 antigen-positive large cel l lymphoma with anaplastic cytologic features. Both the follicular and diffuse/sinusoidal components were of B-cell lineage, positive for th e CD20 antigen and negative for the CD3 and CD43 antigens. The neoplas tic cells expressed monotypic immunoglobulin light chain in five cases , three kappa and two lambda. BCL-2 protein was positive in four tumor s, in both the follicular and diffuse/sinusoidal components in three c ases, and only in the latter component in one case. Using the polymera se chain reaction (PCR), three of six cases had monoclonal immunoglobu lin heavy chain gene rearrangements. The t(14;18) was not amplified in any case. Using reverse transcriptase (RT)-PCR, the t(2;5) was amplif ied in one of four tumors. This report highlights the heterogeneity of B-lineage anaplastic large cell lymphomas and indicates the need to c onsider antecedent follicular lymphoma in any B-cell lymphoma with ana plastic cytologic features.