Pigmented lesions are among the most common findings on skin examination. The challenge for the physician is to distinguish benign lesions from cutaneous melanomas and nonmelanoma skin cancers (NMSCs). Both melanoma and NMSC are increasing in frequency, and melanoma accounts for over half of the deaths resulting from skin cancer. Melanoma is an aggressive malignancy of melanocytes, pigment-producing cells that originate from the neural crest and migrate to the skin, meninges, mucous membranes, upper esophagus, and eyes. Melanocytes in each of these locations have the potential for malignant transformation, but the vast majority of melanomas arise in the skin, often permitting detection at a time when complete surgical excision leads to cure. Cutaneous melanoma can occur in people of all ages and all colors. Examples of malignant melanoma of the skin, mucosa, eye, and nail are shown in Fig. 76-1.
Types of melanoma. A. Hypomelanotic melanoma. B. Superficial spreading melanoma. C. Melanoma arising in a nevus. D. Melanoma arising in a nevus. E. Nodular melanoma. F. Cutaneous melanoma metastases at a surgical margin (also known as melanoma satellites when <2 cm from the primary tumor and in-transit melanoma when >2 cm). G. Mucosal melanoma arising in the vulva. H. Choroidal melanoma with tumor borders marked by arrowheads, color fundus photograph. I. Acral melanoma with Hutchinson’s sign on the proximal nail fold. (Parts A-F and I: Courtesy of the Dr. Leonard Swinyer Collection, © Copyright 2020 University of Utah and Oregon Health & Science University. Part G: Courtesy of Dr. Debbie Miller, © Copyright 2022 Oregon Health & Science University [OHSU]. Part H: Courtesy of Dr. Alison Skalet, © Copyright 2022 Oregon Health & Science University [OHSU].)
RISK FACTORS AND EPIDEMIOLOGY
The epidemiologic patterns seen in melanoma reflect the genetic and biologic features of melanocytes and their response to environmental ultraviolet radiation (UVR). Clinical features that confer an increased risk for melanoma include: (1) vulnerability to sun damage (light/red coloration of skin, hair, or eyes; photodamaged skin; history of exposure to natural or artificial UVR; prior history of skin cancers of any type); (2) abnormal growth of melanocytes (increased absolute number of nevi, increased size of nevi, or atypical features of moles such as multiple colors, speckles, or shapes); and (3) immunosuppression (innate, functional, or drug-induced). Table 76-1 summarizes melanoma risk factors and the relative risk associated with these factors.
Table Graphic Jump Location TABLE 76-1Melanoma Risk Factors and Relative Risk ||Download (.pdf) TABLE 76-1 Melanoma Risk Factors and Relative Risk
|RISK LEVEL ||RISK FACTOR ||RELATIVE RISK |
|Elevated ||1 atypical nevus versus 0 ||1.5 |
|Total common nevi, 16+ versus <15 ||1.5 |
|Blue eye color versus dark ||1.5 |
|Hazel eye color versus dark ||1.5 |
|Green eye color versus dark ||1.6 |
|Light brown hair versus ...|