Primary dermal melanoma.

Primary dermal melanoma (PDM) is a rare subtype of melanoma with an estimated incidence of <1%. PDM manifests entirely in the dermis or subcutis and histopathologically mimics cutaneous melanoma metastasis due to its lack of connection to the overlying epidermis. A thorough history and examination, including imaging evaluation for metastatic disease, reveals no prior history or concurrent primary cutaneous or metastatic melanoma lesion. 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.