NUT an Uncommon Cause of Exogenous Acral Hyperpigmentation

Abstract

A cute-onset acral hyperpigmentation can be a concerning clinical finding presentation. Thorough consideration of both endogenous and exogenous etiologies is important for guiding evaluation and management. Endogenous causes include elevated adrenocorticotropic hormone, hemochromatosis, iatrogenic, melanocyte proliferation, subcorneal or intraepidermal hemorrhage, tinea nigra, and vasculitis. Exogenous etiologies include clothing, shoes, and plants. There is limited literature on the latter, especially on acral surfaces and in the pediatric population. We present a case of exogenous acral pigmentation in a young girl. CASEA healthy 11-year-old girl presented to her primary care physician in October in Northeastern America with multiple 0.5-to 3.0-cm well-demarcated brown macules and patches on her bilateral plantar feet, mainly at pressure points (Fig. 1). These asymptomatic lesions had been noticed 1 week prior and persisted through vigorous washing. The patient denied prolonged exposure to water or cold temperatures. She had no personal or family history of skin cancer. During consultation with a pediatric dermatologist, additional history was elicited that the patient had been barefoot in the woods days before noticing the lesions. A diagnosis of exogenous acral hyperpigmentation secondary to barefoot contact with fallen husks of walnut trees was favored. Watchful waiting was recommended. The lesions resolved spontaneously. Figure 1. Asymptomatic brown macules (0.5-3 cm) and patches on the bilateral plantar feet of an 11-year-old girl.