Mitotic figures are usually infrequent. In about a third of cases, noncaseating granulomatous areas containing small giant cells are found. In some seminomas, the neoplastic cells are more pleomorphic and have more mitotic figures than in typical seminoma. These tumors have been called anaplastic seminomas. Left panel shows multinucleate giant cells of foreign body type.
Right panel shows syncytiotrophoblast-like tumor giant cell.
When metastases occur, they tend to involve regional lymph nodes initially, followed by systemic spread. Seminomas containing syncytiotrophoblastic giant cells should not be considered as mixed germ cell tumors. The tumor tends to be poorly demarcated, usually soft with a gelatinous or mucoid appearance. Cystic areas, especially in the center, are common but hemorrhage or necrosis is almost always absent. Spermatocytic seminomas form solid sheets of cells without the nesting pattern of classical seminoma.