Paracicatricial melanocytes as a sign of melanoma.

Intradermal melanocytes in the setting of melanoma represent a diagnostic challenge to dermatopathologists as their presence may represent superficially invasive melanoma vs benign nevus cells or reactive dermal melanocytes. Previous dermatologic literature suggests that the absence of cytologic atypia in intradermal melanocytes and their presence in nonmelanocytic neoplasms lends to their characterization as reactive, benign, melanocytic proliferation. A 67-year-old female presented for evaluation of a 10-mm irregularly pigmented dark brown macule on the left cheek. Initial shave biopsy showed transected malignant melanoma measuring at least 0.6 mm in thickness. Multiple reexcision specimens demonstrated residual melanoma with banal appearing intradermal epithelioid melanocytes within and surrounding the scar. The melanocytes tracked into the skin graft, which had previously been free from involvement. Positron emission tomography-computed tomography (PET CT) and lymph node biopsies did not show evidence of metastatic melanoma. Ten months after her diagnosis and following five surgical excisions, the patient was diagnosed with metastatic melanoma to the brain and succumbed to intracranial hemorrhage. We present a case in which paracicatricial melanoma may simulate benign paracicatricial melanocytic hyperplasia. These findings have significant therapeutic and prognostic implications for the practicing dermatologist and dermatopathologist.