Small cell carcinoma of the ovary. A report of six cases.

Six cases of small cell carcinoma of the ovary are presented. The tumors occurred in women with an average age of 27.5 years. According to the International Federation of Gynecology and Obstetrics (FIGO), two patients had Stage I, three Stage II, and one Stage III disease. The tumors behaved highly malignantly, as four of the patients died from disseminated disease within 20 months. Three of the tumors were found to be associated with elevated serum calcium levels. By light microscopy three of the tumors were originally misinterpreted: one as an undifferentiated tumor, probably of stromal origin; one as a germ cell tumor, probably endodermal sinus tumor; and the third as a granulosa cell tumor. In four tumors examined by electron microscopy, the epithelial nature was confirmed, and three of them contained neuroendocrine granules. Immunocytochemical examination in five cases revealed positive staining for neuron-specific enolase (NSE) and negative staining for beta 2-microglobulin, whereas one case was negative for NSE and positive for beta 2-microglobulin. A positive immunoreaction for parathyroid hormone was observed in three cases (all NSE positive). In two of these a raised serum calcium level was documented. This finding possibly gives a clue to the hypercalcemia so frequently found in these patients.