Primary dermal melanoma: a case report and a review of the literature.

Patients with cutaneous metastatic melanoma of unknown primary origin (stage IV M1a disease according to the American Joint Committee on Cancer melanoma staging system) have an estimated 5-year survival rate of between 5% and 17.9% and a median survival of 6 months. However, certain patients with stage IV M1a disease have much higher survival rates. The existence of this subpopulation has given rise to the term primary dermal melanoma to describe such cases. We report a case of melanoma with characteristics consistent with primary dermal melanoma and review the relevant literature. A diagnosis of primary dermal melanoma requires careful clinical and pathologic correlation and should be considered in all patients with a solitary melanoma confined to the dermis and subcutaneous tissue when there is no evidence of a primary tumor or disease at other sites following appropriate staging studies. We believe that familiarity with this subtype of melanoma is essential in order to provide patients with optimal care and better prognostic information.