Snapshot A 43-year-old man presents to his primary care physican for a pigmented lesion on his right forearm. He has had multiple sunburns in the past and works as a farmer, spending most of the day outside. Physical examination is notable for a 7-mm hyperpigmented lesion that is asymmetric with irregular borders and color variation. He undergoes an excisional biopsy, which demonstrates larger than normal melanocytes of various sizes with large hyperchromatic nuclei in the lower epidermis and dermis. Introduction Overview malignant tumor of melanocytes login to view 15 more bullets Epidemiology Incidence most commonly seen between the ages of 40-60 Risk factors dysplastic nevi multiple nevi ultraviolet radiation exposure fair-skin color immunsuppresion ETIOLOGY Pathophysiology Clark model of pathogenesis login to view 4 more bullets Presentation Physical exam pigmented skin lesion login to view 6 more bullets Studies Serum labs S-100 tumor marker Invasive studies excisional biopsy login to view 12 more bullets Differential Actinic keratosis differentiating factors login to view 2 more bullets Basal cell carcinoma differentiating factors login to view 3 more bullets Treatment Medical vemurafenib login to view 3 more bullets Surgical local wide excision login to view 2 more bullets Complications Metastatic melanoma lung brain liver bone intestines Prognosis Prognostic favorable favorable login to view 1 more bullet negative login to view 1 more bullet