Criteria for aspiration cytology for the diagnosis of seminoma.

Fine-needle aspiration cytology was performed in two cases of intra-abdominal tumors, one from retroperitoneal lymph nodes and one from a cryptorchid testis. The cytological diagnosis was consistent with seminoma in both cases. Cytological features included uniform neoplastic malignant cells with round nuclei and nucleoli. The cytoplasm, easily observed on May-Grünwald-Giemsa-stained smears, contained large vacuoles or lacunes filled with glycogen. Alkaline phosphatase activity was strictly located to one cytoplasmic area of the cells. This cytological and cytoenzymatic pattern is different from that observed in other intra-abdominal tumors, including adenocarcinoma, large-cell lymphoma, and embryonal carcinoma.