androgenic alopecia; androgenetic alopecia; male balding pattern

Introduction

also see alopecia &/or pattern alopecia

Epidemiology

• most common cause of alopecia in men
  • 50% of men at age 50 years; 70% at age 70 years
• can effect men or women

Pathology

• dihydrotestosterone promotes involution of hair follicles in genetically-prone men
• non-scarring alopecia

Genetics

• generally inherited trait
• autosomal dominant with mixed penetrance
• homozygous mutations of WNT10A cause recessive odonto-onycho dysplasia & sparse scalp & body hair (WNT signaling occurs normally in hair development & hair cycling)

Clinical manifestations

• men
  • receding hairline
  • baldness on the top of the head
  • gradual thinning in the temporal areas
  • the hair loss in an area is not complete
• women
  • hair generally is lost diffusely over the crown resulting in a gradual thinning of the hair, widest anteriorly
    • a widening of the central part may be noted
    • the hair loss in an area is not complete
  • the frontal hairline is often preserved in women
  • bitemporal recession to a lesser degree than in men

* images

Complications

• cardiovascular risk factor, especially, baldness at the crown of the head

Differential diagnosis

• alopecia areata is generally associated with an area of marked baldness
• telogen effluvium is trigerred by a stressful event
  • commonly seen in post-partum women

Management

• men
  • some men elect to forgo treatment
  • topical minoxidil 5% BID
    • best results with patients < 30 with < 5 years hair loss
  • oral finasteride or dustateride
• women
  • topical minoxidil 2% (Rogaine) BID
  • spironolactone
• surgical procedures
  • hair transplant
  • scalp reduction
  • flaps

More general terms

• pattern alopecia