Recurrent Melanoma In Situ at the Skin Graft Site of a Prior Malignant Melanoma of the Left Upper Extremity: A Case Report

We present the case of a 43-year-old Caucasian, fair-skinned male with a history of multiple malignant melanomas, who presented in February 2024 for excision of a new melanoma arising within a prior skin graft. The graft had been harvested from his thigh to close an excision of a primary malignant melanoma with a depth of 0.73 mm in 2018. Extensive pathologic interrogation, as well as systemic work-up - including positron emission tomography and computed tomography scans - was performed to determine whether this lesion represented local recurrent disease or a new primary melanoma. This workup was consistent with a primary melanoma in situ, which led to the decision to proceed with skin graft resection and full-thickness skin grafting from his lower left abdomen. The entire previous skin graft was excised. Subsequent surgical pathologic examination of the excised skin graft demonstrated no residual malignant melanoma. This interesting case demonstrates a unique site of primary melanoma occurrence in a split-thickness skin graft. While this may be the result of incomplete tumor resection at the primary operation, the initial excision had wide margins of 2 cm, and pathological examination demonstrated negative margins. Additionally, the skin graft harvest site was carefully selected, as it came from a relatively sun-protected site. This presentation highlights the importance of continued surveillance of melanoma excision sites, warning patients of possible tumor recurrence or new primary occurrence, and setting expectations that incidental findings may occur.