Fine-needle aspiration cytology of seminoma: a review of 16 cases.

We report the cytomorphologic features of 16 fine-needle aspiration (FNA) biopsies of seminoma obtained from 16 male patients. The aspirates included two primary gonadal tumors (one occurring in a cryptorchid testis), two primary mediastinal tumors, and 12 metastases (two with unknown primaries). Analysis of the aspirates revealed a primarily dispersed cell population of large cells with scant to moderately abundant cytoplasm. The nuclei were round to slightly irregular, had finely granular chromatin, and had either one central prominent nucleolus or two to three smaller nucleoli. Variable numbers of lymphocytes and plasma cells were intermingled with the tumor cells. Only a few cases had epithelioid histiocytes or the characteristic "tigroid" background. The cytologic features of the metastases were distinctive and were considered diagnostic for therapeutic management. In six cases, an initial diagnosis of seminoma by FNA biopsy identified the neoplasm as germ cell in origin rather than other neoplasms in the differential diagnosis, thereby expediting therapeutic management.