The Becker Nevus Syndrome (BNS) is one of the epidermal nevus syndromes (ENS) and is a hyperpigmented hamartoma rather than melanocytic disorder.
Components of Becker Nevus Syndrome:
(1) nevus
(2) associated malformations
Features of the Becker nevus:
(1) Area of melanosis with sharp borders but an irregular shape ("archipelago-like").
(2) Hypertrichosis may be present within the lesion, and it may be extensive ("hairy").
(3) Most often unilateral and on the chest and shoulder region but it can be found elsewhere.
(4) Expression is androgen-dependent, so features more prominent in males with growth at puberty.
(5) May be present at birth.
(6) Microscopically the lesion shows slight acanthosis, pigmentation of the basal layer of the epidermis and smooth muscle bundles in the dermis.
Associated malformations:
(1) ipsilateral breast hypoplasia
(2) musculoskeletal malformations (extremities, thorax, vertebra)
(3) scoliosis
(4) maxillofacial dysplasia
(5) supranumerary nipple
Other findings:
(1) adrenal hyperplasia
(2) lipodystrophy
