ABSTRACT
Non-Hodgkin’s lymphomas (NHLs) are neoplasms that arise from either B or T lymphocytes, or rarely from cells of the moncyte/histiocyte series. The Rappaport classification of NHL, introduced in 1956, was widely used by pathologists. Plasma cells secrete immunoglobulin in the medullary cords of the lymph node. Most cases of large cell NHL that arise in the setting of chronic lymphocytic leukemia /small lymphocytic lymphoma have been shown to represent histologic progression of the neoplastic clone. The neoplastic cells show a spectrum of differentiation that ranges from small mature-appearing lymphocytes to plasma cells. The extent of plasmacytoid differentiation varies between cases, and may be subtle or marked. Immunohistochemical stains for immunoglobulin light chains performed on core biopsy or clot sections are the single most helpful technique to distinguish malignant from reactive plasma cell proliferations. Plasma cell myelomas and plasmacytomas have clonal immunoglobulin heavy- and light-chain gene rearrangements.
