Melanoma in situ (MIS) arising on chronically sun-damaged skin (also known as lentigo maligna) usually presents as a large hyperpigmented patch on the face of elderly patients. While MIS is itself a nonlethal neoplasm, it can develop foci of invasive disease that can carry the same prognostic implications as those associated with any invasive melanoma.1
Recently, Ahmen and Berth-Jones2 reported successfully treating a case of MIS on sun-damaged skin with topical 5% imiquimod cream. Based on the success of Ahmen and Berth-Jones, we treated our patient's large, recurrent MIS with topical imiquimod. We observed a clearance of the MIS. However, our patient's clinical course was complicated by the development of invasive amelanotic melanoma with satellite lesions.
Fisher GH, Lang PG. Treatment of Melanoma In Situ on Sun-Damaged Skin With Topical 5% Imiquimod Cream Complicated by the Development of Invasive Disease. Arch Dermatol. 2003;139(7):945-947. doi:10.1001/archderm.139.7.945