Primary malignant melanoma of the ovary.

Primary malignant melanoma of the ovary is an exceedingly rare pathologic event: only eight cases have been reported in literature and in every case they arised in a cystic mature teratoma. The differential diagnosis of primary malignant melanoma is a challenge for pathologist: in fact it must be differentiated by metastatic melanoma and by numerous primary ovarian tumours. We report a rare case of primary malignant melanoma of the ovary with immunohistochemical and ultrastructural study and with a review of the literature.