Snapshot A 46-year old woman presents to her primary care physician for a dark spot on the back of her right hand. She states that the spot first appeared about 2 years ago and has slowly been growing. It does not burn, itch, or sting. She has a history of regular suntanning and minimal sunscreen use. On exam, there is a 2-cm, asymmetric, thin, brownish-blue plaque with somewhat ill-defined borders and an irregular pattern of coloration. Introduction Overview malignant tumor of melanocytes most commonly affects the skin login to view 5 more bullets melanocytes are of neural crest cell origin 4 types of cutaneous invasive melanoma login to view 8 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 Pathophysiology Clark model of pathogenesis melanocytes proliferate to form a benign nevus genetic mutations (e.g., BRAF) lead to the nevus to become dysplastic (pre-malignant) login to view 5 more bullets Prognosis prognostic favorable favorable login to view 1 more bullet negative login to view 1 more bullet Presentation Physical exam pigmented skin lesion ABCDEs login to view 5 more bullets Studies Serum labs S-100 tumor marker Invasive studies excisional biopsy indication login to view 1 more bullet findings login to view 9 more bullets Differential Actinic keratosis differentiating factors secondary to proliferation of atypical epiderminal keratinocytes lesions are small, rough papules that are erythematous or brownish Basal cell carcinoma differentiating factors lesions are waxy, pink, and pearly login to view 1 more bullet histology demonstrates palisading nuclei Treatment Medical vemurafenib indication login to view 2 more bullets can lead to T cell mediated destruction of malignant melanocyte Surgical wide local excision indication login to view 1 more bullet Complications Metastatic melanoma lung brain liver bone intestines