• Clinical science

Alopecia

Summary

Alopecia is the loss of hair from any hair-bearing area of the body, but most often the scalp. It may be congenital or acquired, circumscribed or diffuse, and cicatricial or nonscarring. Androgenetic alopecia, a type of diffuse, nonscarring, acquired alopecia, is the most common, affecting > 70% of the general population by 70 years of age. Alopecia areata, an acquired, circumscribed, nonscarring alopecia, is the next most common type. Clinical diagnosis is usually possible. In ambiguous cases, diagnosis is aided by microscopic examination of the hair, trichograms, and scalp biopsy. Treatment depends on the type of alopecia and includes long-term (at least 1 year) use of topical minoxidil, corticosteroids (topical, intralesional, or oral), or antiandrogens. Surgery (hair transplant) or camouflaging techniques are used when medical therapy fails. The prognosis is variable and depends on the etiology and severity of hair loss.

Overview

Definitions

Phases of hair growth

  • Anagen phase: phase of active growth
  • Telogen phase: resting phase
  • Catagen phase: phase of follicular regression

Classification

According to etiology (congenital/acquired) and pattern (diffuse/circumscribed) According to scarring or nonscarring types
  1. Cicatricial (scarring) alopecia
  2. Nonscarring alopecia

Diagnosis

  • The diagnosis is often clear from the patient history and physical examination.
  • Hair pull test: About 50 strands of hair are lightly tugged away from the scalp; if > 5 strands can be pulled out, the test is positive.
  • Dermoscopy: examination of the scalp skin, follicle size and hair shaft diameter by magnification
  • Microscopic examination of hair follicles and shaft: to determine the phase of hair growth (anagen, telogen) and structural abnormalities of the shaft
  • Scalp biopsies from sites of active disease: to confirm diagnosis of cicatricial alopecia
  • Trichograms: aids diagnosis and prognosis of nonscarring alopecia

References:[1][2][3][4][5][6][7][8][9][10]

Diffuse alopecia

Androgenetic alopecia

Androgenetic alopecia in men (male pattern baldness) Androgenetic alopecia in women (female pattern baldness)
Clinical features
  • Gradual, nonscarring hair loss
    • Bitemporal "M” pattern of recession
    • May be followed by hair loss on the vertex of the scalp
    • 10% of men have a female pattern of balding.
  • Follicular miniaturization is seen in the affected parts
  • Gradual, nonscarring hair loss
  • Begins at the vertex
  • Progresses to a more diffuse hair thinning of the entire scalp
Diagnosis
  • Clinical
  • Often clinical
  • In hyperandrogenism: Endocrinological analysis is indicated.
Treatment
  • First-line treatment: finasteride or 5% minoxidil
  • Hair transplant surgery: Follicular units from the occipital scalp are extracted (either as small units or as a linear strip), divided into small units, and implanted into the bald areas.
  • Camouflage: keratin fibers, hair dyes, toupées, etc.
Prognosis

Telogen effluvium

References:[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]

Circumscribed alopecia

Alopecia areata

References:[6][26][27][28][29][30][31][32][33][34][35][36][37]