Female Genital Tract, Mature cystic teratoma

Mature cystic teratoma is a benign germ cell tumour, and the most common benign ovarian tumour. In this case, the tumour presents not as an ovarian mass, but as a large cystic retroperitoneal mass involving the soft tissues surrounding the kidneys, pancreas, and spleen. Grossly, a large cyst can be seen adhering to the spleen. The whole slide image shows benign splenic tissue with a thick-walled cyst lined by squamous epithelium. Granulomatous reaction can be seen, similar to the findings seen in an ovarian dermoid cyst (the most common form of mature cystic teratoma).