In these patients, the lesions of AN are of varying severity. Acral AN is most common in dark-skinned individuals, especially those of African American descent. The hyperkeratotic velvety lesions are most prominent over the dorsal aspects of the hands and feet. Unilateral AN, sometimes referred to as nevoid AN, is believed to be inherited as an autosomal dominant trait. Lesions are unilateral in distribution and may become evident during infancy, childhood, or adulthood.
Lesions tend to enlarge gradually before stabilizing or regressing.
Familial AN is a rare genodermatosis that seems to be transmitted in an autosomal dominant fashion with variable phenotypic penetrance. The lesions typically begin during early childhood but may manifest at any age. The condition often progresses until puberty, at which time it stabilizes or regresses. Drug-induced AN, although uncommon, may be induced by several medications, including nicotinic acid, insulin, pituitary extract, systemic corticosteroids, and diethylstilbestrol. The lesions of AN may regress following the discontinuation of the offending medication.