An incidental finding
Pruritic patches on the patient’s trunk and extremities prompted his visit, but it was the “birthmark” on his back that was far more worrisome.
Diagnosis: Melanoma
The patient underwent elliptical excisional biopsy of the primary lesion after no palpable lymphadenopathy was noted. The lateral and deep margins were negative for melanoma; the mitotic rate was <1/mm2. Aggregates of lymphocytes were associated with the lesion, but did not infiltrate it. There was no tumor regression or ulceration of the lesion. The Breslow depth was 1.25 mm.
A histopathologic evaluation revealed a superficial spreading melanoma (inferior lesion in the FIGURE) and a nodular lesion (the superior reddish-black lesion in the FIGURE). (For more on these and other forms of melanoma, see “The 4 main types of melanoma”1-4 see below.) It was unclear from the patient’s history whether this represented 2 types of melanoma (superficial spreading and nodular) in the same field of skin or the development of a nodular component in a superficial spreading lesion. Important clinical information was also missing, including the evolution of the lesions and how quickly the nodule had grown.
Who’s affected most? More than 45,000 cases of melanoma occurred in 45 states and the District of Columbia annually between 2004 and 2006, according to a 2011 report from the Centers for Disease Control and Prevention.5 White, non-Hispanics have a far higher incidence of melanoma than any other race or ethnicity.6 Women are more likely than men to be diagnosed with melanoma early in life, while men are twice as likely as women to be diagnosed after age 60.6 The etiology for the malignant transformation of melanocytes has not been fully clarified, but it is likely multifactorial, including genetic susceptibility and ultraviolet (UV) radiation damage.4
The ABCDE mnemonic is widely taught to aid in the detection of melanomas: A = asymmetry of the lesion; B = border irregularities; C = color variegation; D = diameter >6 mm; and E = evolution. The evolution of the lesion has been shown in some studies to be the most specific finding for detecting melanomas.4
Regional lymph nodes should also be carefully examined for evidence of clinical spread prior to biopsy of a suspicious lesion. This is important because biopsy may cause regional lymphadenopathy, which could confound later examinations and staging of the disease.1
