A 74-year-old male presented with a progressively enlarging, irregular, pigmented lesion on the nasal supratip that evolved over one year. The lesion demonstrated concerning features, including darkening, asymmetry, and a rough, raised surface, prompting a shave biopsy. Histopathologic evaluation revealed a poorly circumscribed proliferation of atypical melanocytes confined to the epidermis, arranged in a lentiginous pattern, with associated solar elastosis and adnexal extension. The diagnosis of melanoma in situ, lentigo maligna type, was established, with positive peripheral and deep margins. The patient had significant chronic sun exposure due to long-term outdoor occupational work and no personal or family history of skin cancer. He subsequently agreed to undergo Mohs micrographic surgery for definitive treatment. This case highlights the importance of early recognition of suspicious lesions, particularly in sun-exposed areas, and underscores the role of Mohs surgery in achieving tissue-sparing, effective management of melanoma in situ.