The significance of giant cells in human testicular seminomas. A clinico-pathological study.

In order to study the nature and significance of various giant cells encountered in seminomatous tumors of the testis, we reviewed the morphology of 243 consecutive pure seminomas and 107 combined (mixed) tumors, as well as the long term clinical follow-up in 26 patients. Giant cells were grouped into histiocytic or neoplastic ones and the latter subtyped according to morphologic and immunocytochemical characteristics. Neoplastic giant cells were found in 34.6% of all pure seminomas and in 11.2% of all combined tumors, i.e. twice as often as histiocytic giant cells in either tumor group. The various types of neoplastic giant cells were found alone or in combinations with other types. Giant cells capable of elaborating B-HCG were seen in 19.3% of all pure seminomas and in 9.3% of seminomatous components of combined tumors. These incidences argue strongly against a trophoblastic element infiltrating a seminoma from a concomitant occult choriocarcinomatous focus. Large mononuclear giant cells, seen in spermatocytic seminomas, were observed in 15.6% of all pure seminomas, particularly in combination with B-HCG producing giant cells. Another type, characterized by marginated nuclei and eosinophilic cytoplasm were invariably part of a mononuclear cell population of similar features and encountered focally in 9.1% of all pure seminomas. Clinical follow-up, particularly in cases with B-HCG positive giant cells, revealed that treatment as for conventional seminomas at an early stage at least is followed by an excellent course.