Malignant melanoma arising in an ovarian mature cystic teratoma - a rare entity.

Mature cystic teratomas, also known as dermoid cysts, are composed of a mixture of tissues derived from all three germ layers and constitute about 20% of all ovarian neoplasms. However, malignant transformation in a mature cystic teratoma is an uncommon event occurring only in about 1.8% cases. A variety of tumours can arise within a mature cystic teratoma (most common being squamous cell carcinoma), with malignant melanoma being extremely rare among such tumors. While most authors believe that primary ovarian melanoma almost always arises within a mature cystic teratoma, the primary nature of an ovarian malignant melanoma can be ascertained only once metastasis from a cutaneous melanoma is ruled out. The first case of malignant melanoma arising in an ovarian mature cystic teratoma was reported in 1901 and only about 45 additional cases have been reported till date. We present another case of a primary malignant melanoma arising within a mature cystic teratoma.