Becker's nevus

Introduction

Common, acquired benign pigmentary hamartoma.

Epidemiology

• teenage boys
• incidence 0.52% males 17-26 years of age
• onset:
  • 50% before age 10
  • 25% age 10-15
  • 25% after age 15
• male/female ratio 5:1

Pathology

• benign nevoid hypermelanosis
• acanthosis, regular with some hyperkeratosis
• occasional horn cysts
• no nevomelanocytes present
• melanocytes in normal numbers
• basal layer keratinocytes packed with melanin

Genetics

familial cases reported

Clinical manifestations

• unilateral patchy brown hyperpigmentation
• generally occurs on shoulders
• lesions 1st appear at puberty
  • hair generally not present at the onset of hyperpigmentation
  • terminal hair (dark & coarse) generally appears within 1 year
  • hypertrichosis frequently develops several years later
  • increased hair growth localized to hyperpigmented areas
• large, singular plaque
  • mean size 125 cm2
  • jagged edges
• light tan or brown; not uniform color
• barely palpable
• distribution:
  • shoulder & submammary area 32%
  • lower back 23%
  • upper back 19%
  • submammary 13%
  • arms 3%
  • legs 3%

* images

Laboratory

skin biopsy if indicated

Differential diagnosis

• giant congenital melanocytic nevus
  • present at birth
  • distinctly elevated
• Albright's disease
  • congenital
  • no hair
  • pigmentation uniform

Management

• prognosis:
  • pigmentation extends for 1-2 years, then remains stable
  • fading is rare
  • benign lesion; cosmetic concern only

More general terms

• nevus
• hamartoma