Granulocytic sarcoma of the testis: a report of two cases of a neoplasm prone to misinterpretation.

: We report the cases of two men, aged 48 and 71 years, with granulocytic sarcoma of the testis. Both presented with left testicular swelling and underwent orchiectomy, which revealed cream-colored to yellow-tan, rubbery-to-firm, testicular tumors with extensive paratesticular spread. The tumor in the younger patient was composed of a uniform population of primitive cells with scant cytoplasm and was initially misinterpreted as malignant lymphoma. Staging revealed no extrascrotal spread. The patient was treated with radiation and chemotherapy and remained free of disease for 12 years, at which time he died of unrelated causes. The older patient had a history of a myelodysplastic syndrome. His tumor contained cells with bright eosinophilic, occasionally granular cytoplasm, consistent with myeloid lineage. Because of a prominent component of myelocytes, with round, eccentric nuclei and moderately abundant cytoplasm, and because of an associated chronic inflammatory cell infiltrate that contained mature plasma cells, the tumor was initially misinterpreted as a plasmacytoma, although it was reinterpreted as a granulocytic sarcoma before initiation of therapy. Tumor cells in both cases were positive with a chloroacetate esterase stain. Immunohistochemical staining revealed expression of myeloperoxidase, lysozyme, leukocyte common antigen, and CD43, but not of B-cell-specific or T-cell-specific antigens in both cases. Granulocytic sarcomas are apt to be misinterpreted as other hematolymphoid tumors, which may result in a significant error in management. The diagnosis should at least be thought of any time the diagnosis of malignant lymphoma or plasmacytoma of the testis is being considered.