• Clinical science

Alopecia

Abstract

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

  • Alopecia: : loss of hair (baldness)
  • Effluvium : process of hair loss
  • Atrichia : inherited hair loss
  • Hypotrichosis : congenital sparse hair, which is usually associated with syndromes such as Netherton syndrome and Rothmund-Thomson syndrome

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

Congenital diffuse alopecia

  • Trichorrhexis nodosa: A hair shaft deformity characterized by the development of weak points in the shaft due to physical/chemical trauma in genetically predisposed individuals.
  • Pili torti: The hair shaft is flattened and has multiple twists → fragile hair which breaks easily
  • Monilethrix (beaded hair): Autosomal dominant disorder with beaded hair shafts which break easily, close to the scalp, a few months after birth.
  • Genetic syndromes: Menkes disease, Netherton's syndrome, etc.

Acquired 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
  • Grades of thinning
    • Grade I: hair thinning in the forehead region
    • Grade II: rarefaction of the frontoparietal region
    • Grade III: hair loss in the frontoparietal region
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.
  • 2% Minoxidil: first-line treatment
  • Oral antiandrogens
  • Surgery and camouflage
Prognosis

Telogen effluvium

Anagen effluvium

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

Circumscribed alopecia

Congenital circumscribed alopecia

  • Temporal triangular alopecia
    • A well-defined oval/triangular patch of alopecia in the temporal part of the scalp
    • Seen before 5 years of age
    • Mimics alopecia areata and is differentiated from it by the presence of vellus hair and the absence of exclamation point hair
    • Treatment (if necessary):hair transplant/surgical excision
  • Nevus sebaceus
    • A well demarcated hamartomatous lesion predominantly composed of sebaceous glands
    • A solitary hairless, velvety, orange/tan plaque
    • Seen in infancy/early childhood
    • Risk of malignant degeneration (basal cell carcinoma, squamous cell carcinoma, etc.), esp. at puberty
    • Treatment: Surgical excision before puberty
  • Aplasia cutis congenita
    • Intra-uterine developmental disruption of one/more layers of the scalp
    • A part of the scalp is missing at birth, which, on healing → scarred, hairless patch
    • Treatment: Small lesions: no treatment; Large lesions: surgical excision + primary closure/repair (with help of tissue expanders and skin flaps)

Acquired circumscribed alopecia

Alopecia areata

Traction alopecia

  • Hair loss due to chronic traction/tension on the hair follicles, mostly at the frontal and temporal scalp
  • Etiology: Hairstyles involving tying the hair tightly
  • Treatment: Avoid tight hairstyles; Topical minoxidil/steroids

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

Alopecia in chronic and subacute diseases (chronic, diffuse, permanent alopecia)