#00064320

A 91-year-old woman presented with an enlarging left axillary lymph node. Core biopsies showed large atypical lymphoid cells in a background of small mature lymphoid cells, with bizarre atypical giant cells, and necrosis. The cells of interest showed abundant cytoplasm, open chromatin, and prominent nucleoli with round to oval nuclei and occasional Azzopardi effect seen (Fig. A-C). Immunostaining revealed the neoplastic cells to be positive for CD45, CD20, CD5, BCL-6, BCL-2, and MUM-1. Ki-67 highlighted 50% of neoplastic cells (Fig. D). The neoplastic cells showed overexpression of MYC protein by immunohistochemistry. CD3 highlighted background T-cells. The neoplastic cells were negative for CD117, CD10, cytokeratin, CAM 5.2, TdT, CD34 and Cyclin-D1. Flow cytometric immunophenotyping identified an aberrant CD5(+), CD10(-) B cell population with monotypic expression of lambda light chain. FISH demonstrated a BCL6 rearrangement of with a deletion of the 5' region of the gene. FISH also demonstrated extra copies of MYC (8q24), IGH (14q32) and CCND1(11q13) without evidence of MYC or BCL2 rearrangement. The overall findings are diagnostic of a diffuse large B-cell lymphoma, CD5+, with non-germinal center B-cell-like immunophenotype.