dermatologic disorders
Melanoma
Introduction
Malignant melanoma arises from melanocytes in a pigmented area (eg, skin, mucous membranes, eyes, or central nervous system). Metastasis is correlated with depth of dermal invasion. With metastasis, prognosis is poor. Diagnosis is by biopsy. Wide surgical excision is the rule for operable tumors. Metastatic disease requires systemic therapy but is difficult to cure. (See also Overview of Skin Cancer .) In 2023, approximately 97,610 new cases of melanoma are estimated to occur in the United States, causing an estimated 7,990 deaths ( Key Points ). Lifetime risk is approximately 2.6% for White people, 0.1% for Black people, and 0.6% for Hispanic people. Melanoma accounts for < 2% of total skin cancers diagnosed in the United States but causes most skin cancer deaths. Melanomas occur mainly on the skin but also on the mucosa of the oral, genital, and rectal regions and conjunctiva. Melanomas may also develop in the choroid layer of the eye, in the leptomeninges (pia or arachnoid mater), and in the nail beds. Melanomas vary in size, shape, and color (usually pigmented) and in their propensity to invade and metastasize. Metastasis occurs via lymphatics and blood vessels. Local metastasis results in the formation of nearby satellite papules or nodules that may or may not be pigmented. Metastasis to skin or internal organs may occur, and, occasionally, metastatic nodules or enlarged lymph nodes are discovered before the primary lesion is identified. 