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Becker's Naevus

This PatientPlus article is written for healthcare professionals so the language may be more technical than the condition leaflets. You may find the abbreviations list helpful.

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

BECKER'S NAEVUS -ON BACK (DIS14.jpg)

Aetiology1

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.

Epidemiology

  • It is more common in men.
  • One study reported a prevalence of 0.52% in men aged 17-26 years.4

Presentation1,2

  • 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.3

Diagnosis

The age of onset, site and the fixed nature of the lesion are usually enough to make the diagnosis.

Differential diagnosis5

  • McCune-Albright syndrome (with café-au-lait patches on the skin).
  • Pityriasis versicolor is usually symmetrical and slightly scaly.

Histology3,6

  • 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.

Management1

  • No treatment is necessary except for cosmetic reasons; usually reassurance and a diagnosis are enough.
  • For cosmetic treatment of the lesion:
    • Electrolysis or laser treatment may help with hair removal.
    • Laser treatment can sometimes reduce the pigmentation, but may be ineffective or may worsen the lesion.
    • Fractional resurfacing has also been used to lighten the lesions.3
  • For acne in the lesion, use standard acne treatments.
  • If there is doubt about the diagnosis (e.g. possible melanoma), urgent referral is appropriate.

Prognosis

The naevus remains indefinitely.2

Becker naevus syndrome1,6,7

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:

History

It is named after S. William Becker who first described the lesion in 1949. Becker naevus syndrome was described in 1995 by Happle.


Document references

  1. Becker naevus; New Zealand Dermatological Society (DermNet NZ) September 2010
  2. Becker's Naevus, Dermatology Information System
  3. Grim KD, Wasko CA; Symmetrical bilateral Becker melanosis: A rare presentation. Dermatol Online J. 2009 Dec 15;15(12):1. [abstract]
  4. 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. [abstract]
  5. Rivers JK et al; Becker Melanosis, Medscape, Apr 2010
  6. Cosendey FE, Martinez NS, Bernhard GA, et al; Becker nevus syndrome. An Bras Dermatol. 2010 Jun;85(3):379-84. [abstract]
  7. Steiner D, Silva FA, Pessanha AC, et al; Do you know this syndrome? An Bras Dermatol. 2011 Feb;86(1):165-166. [abstract]

Acknowledgements

EMIS is grateful to Dr N Hartree for writing this article and to Dr Huw Thomas and Dr Richard Draper for earlier versions. The final copy has passed scrutiny by the independent Mentor GP reviewing team. ©EMIS 2011.
Document ID: 4062
Document Version: 22
Document Reference: bgp25995
Last Updated: 15 May 2011
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