Seminoma Components Research Articles

Profiles of epitope-defined markers in sera from patients with testicular germ cell tumors

Epitope-defined tumor markers of AFP (FA), HCG (PM), PLAP (H7) and CEA (D/AH) were determined by monoclonal antibodies in sera of patients with germ cell tumors of the testis. Characteristic profiles of PLAP (H7) were seen in localized and metastatic seminoma and in sera of patients with mixed tumors with seminoma components. PLAP (H7) levels started to rise 10 months before clinical detection of recurrence in one case. Persisting elevated levels of PLAP (H7) in several cases were indicative of metastatic seminoma. PLAP (H7) occurred rarely in sera of patients with metastasing non-seminomatous tumors. AFP (FA) detected in seminoma sera led to identification of non-seminomatous disease in one case. High AFP (FA) alone occurred in yolk sac tumors, HCG (PM) with AFP (FA) or PLAP (H7) in patients where the tumors had components of teratoma and/or embryonal carcinoma, moderately elevated levels of AFP (FA) and sometimes also HCG (PM) occurred.

Unusual Thymic Seminomas

Although most thymic seminomas have a histologic appearance similar to those arising in the testis, some seminomas undergo pronounced secondary changes that may obscure the diagnosis. We found three cases that showed a combination of reactive follicular hyperplasia (three cases), large cysts (three cases), epithelioid granulomas (two cases), and fibrosis (two cases), to such a degree that the seminoma component was indistinct. Immunoperoxidase staining for keratin in one case highlighted the intimate association of the positively staining thymic epithelial cells with the nonstaining seminoma cells. The seminoma cells in this case were reactive with placental alkaline phosphatase. No other group of thymic or mediastinal tumors, including those of Hodgkin's disease, exhibited this combination of secondary reactive changes to a similar degree. Because of the favorable prognosis of thymic seminomas, these variants should not be confused with other mediastinal tumors.

The significance of giant cells in human testicular seminomas

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.

Eutopic expression of placental-like alkaline phosphatase in testicular tumors.

Very high levels of placental-like alkaline phosphatases (PLAP-like enzymes) were observed in tissues from 13 typical seminomas. Four tumors with seminoma components contained these enzymes to varying degrees, and other testicular tumors had them in smaller or non-detectable amounts. Analysis using monoclonal antibodies produced against the common placental alkaline phosphatase (PLAP) phenotypes and enzyme inhibition studies with amino acids and peptides showed the PLAP-like enzymes present in seminoma to be similar to those PLAP-like enzymes which are expressed in lower amounts in two embryonal carcinomas and in trace amounts in normal testicular tissue. These similarities suggest that the increased expression of PLAP-like enzymes in seminomas results from enhanced eutopic expression of enzymes found in normal testis.