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A 17-year-old boy with a brown patch, hair
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This is a 17-year-old Hispanic boy who was seen by the dermatologist for acne and was also found with this well-demarcated brown patch with very dark hair overlying it and smaller tan macules surrounding it. He is otherwise healthy.
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Answer
This is a Becker’s nevus.
First described in 1949 by Samuel William Becker, MD, this skin finding is actually a smooth muscle hamartoma; that is, an overabundance of normal tissue. This is sometimes found at birth but more often arises as a light tan or gray patch during childhood. By later childhood or early adolescence, the patch expands in an irregular fashion, becomes much darker and shows terminal hair differentiation. There are often satellite macules and patches of pigmentation surrounding the larger patch.
The occurrence is much greater in men, and familial cases have been reported. Most often seen on the back overlying the scapula, Becker’s nevus has also been reported in other areas of the trunk, face, arms, legs and buttocks. Although this dark brown patch is clinically similar in appearance to a melanocytic nevus, the Becker’s nevus has no malignant potential.
There are several reports of associated abnormalities, including unilateral breast hypoplasia, limb asymmetry and overlying skin diseases limited to the area of the Becker’s nevus itself. The etiology of the lesion is not known; however, there are some theories that support an over expression of androgen receptors in the underlying tissue.
Treatment is not necessary other than for cosmetic reasons and could be undertaken with laser therapy or surgical excision; however, the success of these techniques is variable. The overlying hair may be removed with depilatories or with laser.
Christopher M. Bohyer, MD, is Chief Resident in the Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana.
For more information:
- Danarti R, Konig A, Salhi A, et al. Becker’s nevus syndrome revisited. J Am Acad Dermatol. 2004;51: 965-969.
- Weinberg JM, Scheinfeld N, Tishler HR. Granuloma annulare restricted to Becker’s naevus. Br J Dermatol. 2004;151:245-246.
- Welsch MJ, Stein SL. A syndrome of hemimaxillary enlargement, asymmetry of the face, tooth abnormalities, and skin findings (HATS). Pediatr Dermatol. 2004;21:448-451.
- Carpo BG, Grevelink JM, Grevelink SV. Laser treatment of pigmented lesions in children. Semin Cutan Med Surg. 1999;18:233-243.
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