DISCUSSION
The teenager had a Becker nevus. The histologic findings, natural history, and hypertrichosis were totally inconsistent with giant melanocytic nevus, which is almost always congenital. In tinea versicolor, the lesion would have been slightly scaly, since the disorder represents an epidermal overgrowth of a commensal yeast organism, Malassezia furfur, which could have been found on a potassium hydroxide examination. Tinea versicolor would also have manifested with more irregular pigmentation and would have demonstrated an entirely different histologic picture. The hypertrichosis seen in this lesion, along with the biopsy results, effectively rules out a café-au-lait spot. The latter is worth considering, however, given the potential association with neurofibromatosis type 1.
The shoulder and chest are much more common locations for a Becker nevus, although it has been reported on multiple areas, including the arms and legs (as happened in this patient). The reported incidence is about 0.5%. Boys are affected far more often than girls, and onset almost always coincides with puberty. These two facts, taken along with the hypertrichosis, bolster the case for an androgenic basis for development of a Becker nevus. Even in the unusual patient who lacks hypertrichosis, studies have shown a marked increase in androgen receptors in lesional skin. The appearance and context generally make a Becker nevus very easy to diagnose, although biopsy was done in this case because of the unusual location. Rarely, a Becker nevus has been associated with hypoplasia of adjacent areas, such as breasts, arms, and legs.
Treatment There is no medical reason to treat a Becker nevus. The concerns are strictly cosmetic; these nevi have almost no malignant potential. Laser therapy is possible but carries the usual risks of dyschromia and lesion persistence. As of this writing, the family was mulling treatment options. JAAPA
Joe Monroe works at the Regional Dermatology Clinic, Bartlesville, Oklahoma, and is the department editor for Dermatology Digest. He has indicated no relationships to disclose relating to the content of this article.