Onchocerciasis Presenting With Lower Extremity, Hypopigmented Macules

Onchocerciasis, or river blindness, is a parasitic infection caused by the filarial nematode, Onchocerca volvulus. It infects 18 million people worldwide, but is rarely seen in the United States. It is one of the leading causes of blindness in the developing world. Although onchocerciasis is also known as river blindness, it is not just a disease of the eyes, but rather a chronic multisystem disease. Clinically, onchocerciasis takes three forms: 1) eye disease; 2) subcutaneous nodules; and 3) a pruritic hypopigmented or hyperpigmented papular dermatitis. We present an 18-year-old African female with a 5-year history of asymptomatic, hypopigmented, slightly atrophic macules on her anterior tibiae. Pathology revealed a scant perivascular inflammatory infiltrate with mononuclear cells, eosinophils, and rare microfilariae in the papillary dermis. Ivermectin is the treatment of choice for onchocerciasis and was initiated in this patient. We present this interesting patient with onchocerciasis to expand our differential of hypopigmented macules, especially in the African population. In addition, we discuss both the diagnosis and the treatment of onchocerciasis in expatriate patients living in nonendemic areas.