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Becker's nevus
Common, acquired benign pigmentary hamartoma.
Epidemiology:
1) teenage boys
2) incidence 0.52% males 17-26 years of age
3) onset:
a) 50% before age 10
b) 25% age 10-15
c) 25% after age 15
4) male/female ratio 5:1
Pathology:
1) benign nevoid hypermelanosis [2]
2) acanthosis, regular with some hyperkeratosis
3) occasional horn cysts
4) no nevomelanocytes present
5) melanocytes in normal numbers
6) basal layer keratinocytes packed with melanin
Genetics: familial cases reported
Clinical manifestations:
1) unilateral patchy brown hyperpigmentation
2) generally occurs on shoulders
3) lesions 1st appear at puberty
a) hair generally not present at the onset of hyperpigmentation
b) terminal hair (dark & coarse) generally appears within 1 year
c) hypertrichosis frequently develops several years later [2]
d) increased hair growth localized to hyperpigmented areas
4) large, singular plaque
a) mean size 125 cm2
b) jagged edges
5) light tan or brown; not uniform color
6) barely palpable
7) distribution:
a) shoulder & submammary area 32%
b) lower back 23%
c) upper back 19%
d) submammary 13%
e) arms 3%
f) legs 3%
* images [3]
Laboratory: skin biopsy if indicated
Differential diagnosis:
1) giant congenital melanocytic nevus
a) present at birth
b) distinctly elevated
2) Albright's disease
a) congenital
b) no hair
c) pigmentation uniform
Management:
-> prognosis:
a) pigmentation extends for 1-2 years, then remains stable
b) fading is rare
c) benign lesion; cosmetic concern only
General
nevus
hamartoma
References
- Color Atlas & Synopsis of Clinical Dermatology, Common
& Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY,
1997, pg 302
- Sadlier M, O'Regan GM
Becker's Nevus.
N Engl J Med 2015; 372:1249. March 26, 2015
PMID: 25806917
http://www.nejm.org/doi/full/10.1056/NEJMicm1402443
- DermNet NZ. Becker naevus (images)
http://www.dermnetnz.org/lesions/beckers-naevus.html