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CA0711DermClinic2
A man aged 20 years presented for assessment of a lesion on his back and to discuss treatment options for the hairs growing within. He reported the lesion had been present as long as he could remember. No changes in the shape, color or size of the lesion were described. He reported that his father had a similar lesion on his back. The patient had no notable medical or surgical history.Physical exam showed an irregularly shaped hyperpigmented patch with overlying hypertrichosis. Dermoscopic examination revealed an evenly pigmented brown patch with a benign network pattern in the lesion’s left upper quadrant. Submit your answer and read the full explanation below. If you like this activity or have a suggestion, tell us about it in the comment box at the bottom of the page.
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Becker nevus
The diagnosis of Becker nevus, also known as Becker’s pigmentary hamartoma, was made on the basis of the patient’s history and the results of the physical examination. Becker nevus is a unilateral, hyperpigmented cutaneous hamartoma that usually presents with overlying extra hair growth, known as hypertrichosis. The condition was first observed in 1948 by Dr. S. William Becker.
Patients often report first noticing the lesion in their early teens as an irregular brown patch. As puberty progresses, the lesion grows. With time, localized hypertrichosis occurs, both within and occasionally around the patch. Because the hair is often very thick and dark, patients are frequently prompted at this stage to seek medical consultation for cosmetic recommendations. Some patients develop acne vulgaris within the lesion.1 Typically, the nevus remains unchanged throughout adulthood, although minimal fading may occur.
The most common locations for Becker nevus are the chest, shoulders, and back, although it may be seen elsewhere.
Becker nevus is mostly seen in men; few reports of incidence in women have been documented.2 It is generally considered an acquired disorder, although several researchers report cases that are thought to be congenital. Rarely, it may be familial,3 and as such, is transmitted in an autosomal dominant pattern.
The pathogenesis is uncertain, although androgens are thought to be contributory. This theory is substantiated by documented evidence of male predominance, hypertrichosis, the occasional incidence of acnelike lesions within the growth, and the more rare incidence of an accessory scrotum in a patient with Becker nevus.4 In addition, ligand-binding assays have detected a significant increase in the number of androgen receptors in Becker melanosis lesional skin.
Skin biopsy may help with clinical diagnosis. Histologically, the epidermis demonstrates mild acanthosis, hyperkeratosis, and hyperpigmentation resulting from increased melanin. Occasionally, an increase in the number of basal melanocytes is seen. Ultrastructural examination may reveal giant melanosomes.5 Melanophages are present in the superficial dermis. The increased number of morphologically normal follicular units causes the clinical hypertrichosis. There is an absence of nevus cells.
Interestingly, almost every case of Becker nevus demonstrates at least a slight proliferation of dermal smooth muscles. It is therefore believed that this entity may represent a spectrum with a smooth-muscle hamartoma. Smooth-muscle hamartomas are characterized by an abnormal arrangement of the normally present smooth muscle. Occasionally, Becker nevus may be present along with a clinically evident smooth-muscle hamartoma. These demonstrate more pronounced bundles of smooth muscle irregularly dispersed within the dermis.
No treatment is necessary; however, some patients may request cosmetic interventions for the hypertrichosis or hyperpigmentation. Reports have shown variable success with Q-switched ruby laser (694 nm),6 Er:YAG laser, Nd:YAG system, and long-pulsed 755-nm alexandrite laser. Regular use of sunscreen will prevent any darkening or accentuation of the hyperpigmentation. Electrolysis or waxing can reduce or eliminate hair growth. The acne lesions are treatable with standard topical acne medications, including isotretinoin (Accutane).
Becker nevus is a benign process; however, there was one case of malignant melanoma developing within the nevus. In addition, five other patients developed melanoma in the same region as the Becker nevus. Patients can be reassured that malignancy rates with Becker nevi are the same as in patients without Becker nevi. As with other pigmented lesions, patients should regularly observe for any changes.
Becker nevus is sometimes associated with other muscular, skeletal, or cutaneous abnormalities.7 Becker nevus syndrome describes patients with Becker nevus, ipsilateral breast hypoplasia, scoliosis and—less consistently—other abnormalities.8 Additional associations described in the medical literature include ipsilateral limb shortening, ipsilateral foot enlargement, spina bifida, pectus carinatum, localized lipoatrophy, congenital adrenal hyperplasia, polythelia, and accessory scrotum.
This patient was educated regarding the diagnosis. Laser treatment and hair removal options were discussed. He was told to observe for any changes in the appearance of the lesions. Yearly follow-up was recommended for objective assessment of the Becker nevus and of the junctional nevus within the lesion.
Ms. Stern is a family nurse practitioner at Advanced Dermatology & Skin Surgery, P.C., in Lakewood, N.J. The author has no relationships to disclose relating to the content of this article.
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References
1. Burgreen BL, Ackerman AB. Acneform lesions in Becker’s nevus. Cutis. 1978;21:617-619.
2. Hsu S. Chen JY, Subrt P. Becker’s melanosis in a woman. J Am Acad Dermatol. 2001;45:S195-S196.
3. Book SE, Glass AT, Laude TA. Congenital Becker’s nevus with a familial association. Pediatr Dermatol. 1997;14:373-375.
4. Szylit JA, Grossman ME, Luyando Y, et al. Becker’s nevus and an accessory scrotum. A unique occurrence. J Am Acad Dermatol. 1986; 14:905-907.
5. Bhawan J, Chang WH. Becker’s melanosis: an ultrastructural study. Dermatologica. 1979;159:221-230.
6. Nanni CA, Alster TS. Treatment of a Becker’s nevus using a 694-nm long-pulsed ruby laser. Dermatol Surg. 1998;24:1032-1034.
7. Glinick SE, Alper JC, Bogaars H, Brown JA. Becker’s melanosis: associated abnormalities. J Am Acad Dermatol. 1983;9:509-514.
All electronic documents accessed June 15, 2011
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