Testicular and epididymal plasmacytoma: a report of 7 cases, including three that were the initial manifestation of plasma cell myeloma.

We report the cases of six men, 40 to 89 years of age, with testicular (6 cases) or epididymal (1 case) plasmacytoma. Patients presented with a mass in five cases. One tumor was found during evaluation of progressive myeloma. In the final case, the testicular lesion was identified when the patient presented with pathologic fractures. Gross inspection revealed discrete or, less often, ill-defined lesions. Microscopic examination disclosed masses of atypical plasma cells, including binucleated and multinucleated cells and, occasionally, anaplastic cells that obliterated the underlying parenchyma or invaded between seminiferous or epididymal tubules. Immunohistochemical stains on paraffin sections in five cases showed tumor cell expression of monotypic cytoplasmic immunoglobulin. The cells were positive for the leukocyte common antigen (CD45) in three of five cases. All four cases tested were negative for B (CD20) and T (CD3) cell specific antigens and for CD30 and placental alkaline phosphatase. Expression of CD43, CD45RO, and epithelial membrane antigen was found in three, two, and one of four cases respectively. All the patients also had plasma cell neoplasia distant from the testis, identified before (3 cases), concurrent with (3 cases) or after (1 case) the testicular or epididymal plasmacytoma. In one patient a plasmacytoma developed in the contralateral testis three years later; he was alive with plasma cell myeloma 51 months after diagnosis. Another had a plasmacytoma in the contralateral epididymis 8 years later; he also had a nasal cavity plasmacytoma and multiple subcutaneous plasmacytomas, and was alive and well after 26 years. One additional patient was alive with myeloma 6 months later, and four final patients died between 2 months and 3 years after orchiectomy. Three of the four consultation cases in this series were submitted with diagnoses of spermatocytic seminoma, anaplastic seminoma and lymphoma. The diagnosis of plasmacytoma should be borne in mind when examining testicular or paratesticular tumors with a diffuse pattern without glandular differentiation, particularly in men 40 years of age or older.