Primary Dermal Melanoma.

Primary dermal melanoma (PDM) is a rare subtype of melanoma with an estimated incidence of less than 1%. PDM presents entirely in the dermis or subcutis and histopathologically mimics cutaneous metastases of melanoma due to its lack of connection to the overlying epidermis. A thorough history and examination, including imaging evaluation for metastatic disease, will reveal no prior history or concurrent lesion of primary cutaneous or metastatic melanoma. Despite its histopathologic similarities to melanoma metastasis, PDM is associated with an unexpectedly favorable prognosis. This review discusses the clinical and histopathologic features of PDM as a distinct subtype of melanoma, as well as the current approach to clinical staging and management.