Peritoneal melanosis secondary to a benign dermoid cyst of the ovary: a case report with ultrastructural study.

A case of peritoneal melanosis secondary to a ruptured benign cystic teratoma in a 28-year-old woman is reported. The patient had no history of cutaneous or ocular malignant melanotic lesions. The section of the left ovary contained benign teratoid elements. The ultrastructure of the omental and peritoneal pigmented nodules confirmed that the lesions consisted of histiocytes phagocytizing massive melanin pigments. Although no melanocytic neoplasm was found in the ovarian cystic teratoma, circumstance suggests that the ovarian, omental, and peritoneal pigmented lesions were secondary reactions to melanin released from the ruptured cystic teratoma.