This testicular plasmacytoma is from a 70 y/o male. He had a long-standing history of multiple myeloma and was apparently in remission following chemotherapy and bone marrow transplantation. He presented with progressive enlargement of right testicle and underwent radical orchiectomy. There was a 4.0 cm soft, red mass replacing most of the testicular parenchyma surrounded by a rim of uninvolved tissue. The tumor was positive for CD38, lambda light chains and CD45 (about 10% of cells). The stains for CD20, kappa light chains, placental-like alkaline phosphate and cytokeratin AE1/AE3 were negative. The image shows sheets of immature appearing plasma cells with scattered highly atypical multinucleated cells.