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Synonyms: Becker melanosis, pigmented hairy naevus of Becker
Becker's naevus is a form of epidermal naevus (birthmark). It usually appears around puberty as a hyperpigmented patch, most often found on the upper trunk or shoulders.[1, 2, 3]
There is overgrowth of the epidermis (upper layers of the skin), pigment cells (melanocytes) and hair follicles. It may be due to a gene defect (as yet unidentified), perhaps triggered by circulating androgens, which would explain its onset during adolescence.
- It is more common in men.
- One study reported a prevalence of 0.52% in men aged 17-26 years.
- A large brown area, sometimes covering half the upper back or chest. Most lesions become hairy (hypertrichosis).
- After puberty it often becomes darker and expands, usually over a period of 1-2 years.
- Occasionally acne may develop in the naevus.
- Some fading (reduced pigmentation) may occur in adulthood.
- One case of bilateral, symmetrical pigmentation is reported - this is unusual.
The age of onset, site and the fixed nature of the lesion are usually enough to make the diagnosis.
- McCune-Albright syndrome (with café-au-lait patches on the skin).
- Pityriasis versicolor is usually symmetrical and slightly scaly.
- Epidermis: acanthosis and hyperpigmentation of the basal layer, with elongation and fusion of adjacent rete ridges and variable hyperkeratosis.
- Dermis: hyperplasia of the dermal smooth muscle and melanophages.
- No treatment is necessary except for cosmetic reasons; usually reassurance and a diagnosis are enough.
- For cosmetic treatment of the lesion:
- For acne in the lesion, use standard acne treatments.
- If there is doubt about the diagnosis (eg possible melanoma), urgent referral is appropriate.
The naevus remains indefinitely.
This is a Becker's naevus with additional abnormalities of underlying tissues derived from ectoderm. It is a type of epidermal naevus syndrome. There may be underdevelopment or overdevelopment of underlying structures, including:
- Smooth muscle hamartoma.
- Hypoplasia of breast.
- Spina bifida or scoliosis, pectus carinatum, pectus excavatum.
- Adrenal hyperplasia.
- Asymmetry of limbs, trunk or face.
- Umbilical hernia.
- Supernumerary nipple, accessory scrotum.
It is named after S. William Becker who first described the lesion in 1949. Becker naevus syndrome was described in 1995 by Happle.
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Further reading & references
- Becker Naevus, DermNet NZ, September 2010
- Becker's Naevus, DermIS (Dermatology Information System)
- Grim KD, Wasko CA; Symmetrical bilateral Becker melanosis: A rare presentation. Dermatol Online J. 2009 Dec 15 15(12):1.
- Tymen R, Forestier JF, Boutet B, et al; (Late Becker's nevus. One hundred cases (author's transl)). Ann Dermatol Venereol. 1981 108(1):41-6.
- Rivers JK et al; Becker Melanosis, Medscape, Apr 2010
- Cosendey FE, Martinez NS, Bernhard GA, et al; Becker nevus syndrome. An Bras Dermatol. 2010 Jun 85(3):379-84.
- Steiner D, Silva FA, Pessanha AC, et al; Do you know this syndrome? An Bras Dermatol. 2011 Feb 86(1):165-166.
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