Spontaneous nonmetastatic choriocarcinoma, yolk sac carcinoma, embryonal carcinoma, and teratoma in the testes of a swiss albino mouse.

A 12-week-old Swiss Albino mouse was presented with unilateral (left) testicular enlargement of approximately 1.5 cm in diameter and the right testicle mildly reduced in size and weight. Histopathology evaluation revealed three distinct neoplasms in the left testicle: choriocarcinoma, yolk sac carcinoma, and embryonal carcinoma. Teratoma was diagnosed in the right testicle. The histomorphological and immunohistochemical characteristics of the tumor are presented here. To the best of the authors’ knowledge, this is the first report of spontaneous nonmetastasizing choriocarcinoma, yolk sac carcinoma, embryonal carcinoma, and teratoma in testes of a Swiss albino mouse.