DermDx: Coarse Hairs on Lower Extremity

A Becker nevus is a common benign cutaneous melanocytic epidermal growth. Clinically it presents as a light brown macule with a geographic pattern and sharply demarcated borders. It can be present at birth, but it often appears around the time...

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A Becker nevus is a common benign cutaneous melanocytic epidermal growth. Clinically it presents as a light brown macule with a geographic pattern and sharply demarcated borders. It can be present at birth, but it often appears around the time of puberty with a male-to-female ratio of 5:1. Becker nevus manifests unilaterally on the upper trunk and shoulder with fewer occurrences on the lower trunk and thighs.¹ Typically, the lesion extends for a variable time period and then remains stable in size, rarely fading. It can become darker and hairier throughout puberty, with one-half of cases having hypertrichosis. Androgenic stimulation has been postulated as an underlying factor.²

Differential diagnoses include congenital melanocytic nevi, smooth muscle hamartomas, and café au lait macules. Histologic examination demonstrates a normal number of melanocytes with increased levels of melanin in the basal epidermal layer. Management of a Becker nevus is purely cosmetic; associated hypertrichosis can be treated with laser-assisted hair removal.³ Rates of malignancy are no different in Becker nevi compared with normal skin.⁴

Dr Schiffman is a board-certified dermatologist and director of Miami Skin Dr. in Doral, Florida. Dr Schleicher is director of the DermDox Center for Dermatology, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College. 

References

1. Copeman PWM, Jones EW. Pigmented hairy epidermal nevus (Becker). Arch Dermatol. 1965;92(3):249-251.
2. Person JR, Longcope C. Becker’s nevus: an androgen-mediated hyperplasia with increased androgen receptors. J Am Acad Dermatol. 1984;10:235-238.
3. Lapidoth M, Adatto M, Ben-Amitai D, Cohen S, Halachmi S. Hypertrichosis in Becker’s nevus: effective low-fluence laser hair removal. Lasers Med Sci. 2014;29(1):191-193.
4. Fehr B, Panizzon RG, Schnyder UW. Becker’s nevus and malignant melanoma. Dermatologica.  1991;182(2):77-80.