Lentigo Maligna Melanoma In Situ on Chronically Sun-Damaged Skin

Context.-Cutaneous primary invasive malignant melanoma often is classified by its histologic appearance. Major recognized histologic subtypes of melanoma include superficial spreading, lentigo maligna melanoma, nodular, and acral lentiginous. More recently, it has been shown that most primary invasive melanomas harbor nonrandom genetic or biochemical aberrations that correlate with anatomic site or with the amount of cutaneous exposure to sunlight. It also is generally accepted that most primary invasive melanomas are preceded by an intraepidermal atypical melanocytic proliferation that lacks invasive capability (melanoma in situ). Objective.-To focus on lentigo maligna, the preinvasive/in situ form of melanoma located on chronically sun-damaged skin. Data Sources.-Review of the literature and the authors' personal experiences. Conclusions.-A better understanding of the earliest stage of melanoma progression, including the contribution of chronic exposure to ultraviolet radiation, may lead to improved classification schemes that direct more effective targeted or personalized therapies for patients. (Arch Pathol Lab Med. 2011;135:838-841)