Benign Melanocytic Lesions and Melanoma

Melanoma is a neoplasm comprised of cells with varying degrees of melanocytic differentiation; the incidence of melanoma is increasing and it leads to approximately 9500 deaths annually. Melanoma is thought to be induced primarily by exposure to ultraviolet radiation in genetically susceptible individuals. Although early-stage melanoma is easily cured by excision, metastatic melanoma remains difficult to treat. A key task of a dermatopathologist is to distinguish between benign and malignant melanocytic lesions. Although nevi often contain aberrations in key signaling pathways that are common to melanomas, they have not undergone complete transformation that renders them capable of invasion and metastasis. Using morphological parameters as guidelines, the clinician and pathologist can distinguish between benign and malignant lesions and further classify them according to their appearance, location, and increasingly molecular characterization. Although advancements in molecular biology have enhanced our understanding of melanoma, much remains to be learned regarding its pathogenesis. New treatments utilizing recent discoveries in melanoma genetics have produced targeted therapeutics that both increase our understanding of the disease and extend the lives of patients.