Testicle, Seminoma

Seminoma is the most common malignant testicular germ cell tumour. Histologically it shows uniform cells with abundant clear cytoplasm, well defined cell borders and prominent nucleoli. Gross findings include well circumscribed mass, usually confined to the testis, with homogeneous lobulation and bulging surface. There is usually no evidence of hemorrhage or necrosis.

As shown here, touch prep cytology shows a dimorphic population of large seminomatous cells (uniform round nuclei, prominent nucleoli) and small dark lymphocytes. Other features on cytology include distinct cell boundaries, and no nuclear overlapping. Less frequently, seminomas can have plasmacytoid, rhabdoid or signet ring cell appearance.

For another example of this entity see LMP71477 - Testis, Seminoma (see link in related content).