Dysgerminoma of the ovary an immunohistochemical study of tumor-infiltrating lymphoreticular cells and tumor cells

BACKGROUND: Human neoplasms often are accompanied by an inflammatory infiltrate. It has been proposed that this represents an immunologic response to the tumor. Dysgerminoma, a germ cell tumor of the ovary, is a classic example of this phenomenon. The authors investigated the immunophenotype of the tumor-infiltrating lymphoreticular cells (TIL) and tumor cells in this rare malignancy. METHODS: Tissue from seven dysgerminomas of the ovary was fixed in formaldehyde solution and embedded in paraffin and investigated immunohistochemically with a broad panel of monoclonal antibodies. In one case, additional immunohistochemical investigations were performed on cryopreserved tumor tissue. RESULTS: All seven tumors showed a marked cellular stromal reaction with formation of disseminated granulomas similar to that seen in the closely related testicular seminoma. The TIL were preponderantly T-cells (CD43+, CD45RO+, OPD4+) and macrophages/epithelioid cells (MAC387+, CD68+), B-cells (CD20+, Ki-B3+), natural killer cells (CD57+), and immune-accessory cells (CD1+, CD35+) were rare in most cases. In the one case in which cryopreserved tissue was available, most of the intratumoral T-cells belonged to the CD8+ (cytotoxic/suppressor) subtype, and most of the intratumoral T-cells expressed the alpha/beta heterodimer of the T-cell antigen receptor; gamma/delta + T-cells were exceedingly rare. Some of the macrophages/epithelioid cells were found to express activation antigens (interleukin-2 receptor, transferrin receptor, HLA-DR2). Antibodies against placental alkaline phosphatase and pancytokeratin each stained tumor cells in six cases. Virtually no tumor cells were found to express major histocompatibility complex (MHC) Class II antigens. CONCLUSIONS: The immunohistochemical findings concerning the tumor cells and TIL in dysgerminoma of the ovary provide additional evidence of a close relation to seminoma of the testis.