Malignant lymphoma of plasmablastic identity. A neoplasm with both "immunoblastic" and plasma cellular features.

A solitary extramedullary lymphoid neoplasm had characteristics of plasma cell precursors or plasmablasts. Conventional microscopic study classified this tumor as a diffuse large cell lymphoma of "immunoblastic sarcoma" type. Immunologic cell surface markers could not be detected, but cytoplasmic immunoglobulin G (IgG)-kappa was demonstrated by immunoperoxidase technic, and IgG was present in the supernatant of the tumor tissue culture. The distinction between lymphoid and plasma cellular neoplasms is made.