Harrison's Internal Medicine Chapter 83. Cancer of the Skin Melanoma Pigmented lesions are among the most common findings on skin examination. The challenge is to distinguish cutaneous melanomas, which may be lethal, from the remainder, which with rare exceptions are benign. Examples of malignant and benign pigmented lesions are shown in Fig. 83-1. Figure 83-1 Atypical and malignant pigmented lesions. The most common melanoma is superficial spreading melanoma (not pictured). A. Acral lentiginous melanoma is the most common melanoma in blacks, Asians, and Hispanics and occurs as an enlarging hyperpigmented macule or plaque on the palms and soles. Lateral pigment diffusion is. | Chapter 083. Cancer of the Skin Part 1 Harrison s Internal Medicine Chapter 83. Cancer of the Skin Melanoma Pigmented lesions are among the most common findings on skin examination. The challenge is to distinguish cutaneous melanomas which may be lethal from the remainder which with rare exceptions are benign. Examples of malignant and benign pigmented lesions are shown in Fig. 83-1. Figure 83-1 Atypical and malignant pigmented lesions. The most common melanoma is superficial spreading melanoma not pictured . A. Acral lentiginous melanoma is the most common melanoma in blacks Asians and Hispanics and occurs as an enlarging hyperpigmented macule or plaque on the palms and soles. Lateral pigment diffusion is present. B. Nodular melanoma most commonly manifests itself as a rapidly growing often ulcerated or crusted black nodule. C. Lentigo maligna melanoma occurs on sun-exposed skin as a large hyperpigmented macule or plaque with irregular borders and variable pigmentation. D. Dysplastic nevi are irregularly pigmented and shaped nevomelanocytic lesions which may be associated with familial melanoma. Epidemiology Melanomas originate from neural crest-derived melanocytes pigment cells present normally in the epidermis and sometimes in the dermis. This tumor affects around 62 000 individuals per year in the United States resulting in 7910 deaths. Melanoma is the fifth most common cancer in men 5 of cancers and the sixth most common in women 4 of cancers . The tumor can affect adults of all ages even young individuals starting in the mid-teens has distinct clinical features that make it detectable at a time when cure by surgical excision is possible and is located on the skin surface where it is visible. The incidence has increased dramatically 6 per year from 1973 to 1980 then 3 per year . Current lifetime risk ratio is 1 53 in males and 1 78 in females. The reason for this increase is uncertain but may involve increased recreational sun exposure especially early in .
