Extraocular Sebaceous Carcinoma in Lynch Syndrome: A Sentinel Cutaneous Clue to Muir-Torre Syndrome

Sebaceous carcinoma (SC) is a rare and aggressive cutaneous malignancy, most commonly arising in the periocular region. Extraocular presentations, particularly in patients with Lynch syndrome (LS), are uncommon but clinically significant. We report the case of a 70-year-old male with a known diagnosis of LS and a strong family history of visceral malignancies, who presented with a rapidly enlarging lesion on the forehead. Histopathological examination confirmed extraocular sebaceous carcinoma with a high Ki-67 proliferative index. The lesion was managed successfully with Mohs micrographic surgery (MMS) to ensure complete excision and minimize recurrence. This case fulfilled clinical and molecular criteria for Muir-Torre syndrome (MTS), a phenotypic variant of LS characterized by sebaceous neoplasms and internal malignancies. It underscores the importance of recognizing cutaneous markers of hereditary cancer syndromes and emphasizes the need for prompt dermatological and genetic evaluation in at-risk individuals. Early intervention facilitates timely treatment and familial cancer surveillance.