Acral melanocytic nevi: prevalence and distribution of gross morphologic features in white and black adults.

OBJECTIVE: To determine prevalence and morphologic features of acral melanocytic nevi in white and black adults.
DESIGN: Point prevalence survey.
SETTING: Outpatient dermatology clinic. PATIENTS: Convenience sample of subjects 18 years or older. MAIN OUTCOME MEASURES: Prevalence and morphologic features based on ethnicity, sex, and age.
RESULTS: Palmar or plantar nevi were detected in 42.0% of blacks (50 of 119) vs 23.0% of whites (79 of 343) (P < .001). Palmar or plantar nevi of 6-mm diameter or larger were detected in 3.4% of blacks (4 of 119) vs 0.6% of whites (2 of 343) (P = .04). Diffusely black acral nevi were uncommon in whites (0 of 343) and blacks (1 of 119). The prevalence of palmar or plantar nevi increased directly with degree of skin pigmentation (P < .001). In whites, this prevalence was greater in women (27.1%, 51 of 188) than in men (18.1%, 28 of 155) (P = .047); in subjects younger than 50 years (30.8%, 57 of 185) than in those 50 years or older (13.9%, 22 of 158) (P < .001); in subjects with a history of atypical nevus removal than in those without (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.9-6.9); in those with at least 1 extant atypical nevus than in those without (OR, 3.2; 95% CI, 1.7-6.0); and in those with at least 20 nevi of 2-mm diameter or larger than in those without (OR, 3.0; 95% CI, 1.6-5.6).
CONCLUSIONS: Acral nevi appear to be associated with ethnicity, pigmentation, age, and cutaneous melanoma (CM) risk factors. While relatively large and/or very darkly pigmented acral nevi appear to be more common in blacks than in whites, diffusely black acral nevi are uncommon in both groups. These findings are relevant to the assessment of pigmented lesions in the differential diagnosis of acral CM.