Answer: Seminoma

Histology: This tumor has two histological patterns. The first consists of sheets of cells with clear cytoplasm. The nuclei appear relatively uniform with large central nucleoli. There is a lack of an associated lymphocytic reaction. The second component consists of similar cells with a pseudoglandular pattern of differentiation with scattered lymphocytes. This tumor pattern appears infiltrative in between seminiferous tubules.

Discussion: The cytology of this tumor is typical for that of classic seminoma. Whereas approximately 85% of seminomas have an associated prominent lymphocytic reaction, not all seminomas do so. Embryonal carcinomas would show much greater degree of cytological atypia and cells would not be as loosely cohesive as seen in the current case. Furthermore, most embryonal carcinomas show some evidence of primitive tubular formation. Teratomas contain glandular elements, yet the glandular appearing structures seen in the current case are not true glands. They lack basally situated nuclei and apical cytoplasm. Rather, the cell type is identical to that seen in the solid areas of the seminoma, such that the glandular appearance merely represents a falling apart of tumor cells. Similarly, adenocarcinomas arising in a germ cell tumor would have well defined glands similar to a teratoma yet showing overt malignant cytology resembling adenocarcinoma seen in somatic sites. This pseudoglandular pattern of seminoma has no prognostic significance other than recognizing it as seminoma so that the patient is treated appropriately.