Primary malignant melanoma of the ovary arising in a cystic teratoma; case report and review of the literature.

Primary malignant melanoma of the ovary arising in a cystic teratoma is extremely rare. There is no melanocytic component in the normal ovarian tissue. However, melanocytes may be present in a cystic teratoma of the ovary, especially at the basal layer of squamous epithelium. We report a case of primary malignant melanoma of the ovary arising in a cystic teratoma. We demonstrate junctional activity of melanocytes showing malignant transformation with both radial and vertical growth phases, a feature diagnostic for primary malignant melanoma but not always demonstrated in such cases. We compiled and reviewed twelve cases that are also able to demonstrate junctional activity.