Written and peer-reviewed by physicians—but use at your own risk. Read our disclaimer.

banner image

amboss

Trusted medical answers—in seconds.

Get access to 1,000+ medical articles with instant search
and clinical tools.

Try free for 5 days

Alopecia

Last updated: February 10, 2021

Summarytoggle arrow icon

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.

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:

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)

Classification of alopecia according to etiology and pattern
Congenital Acquired
Diffuse
Circumscribed

According to the presence of scarring

  • Cicatricial (scarring) alopecia
    • Brocq pseudopelade
      • Seen in women 30–55 years of age
      • Irregular areas of irreversible hair loss, which become scarred areas at a later stage
    • Lichen planopilaris
    • Frontal fibrosing alopecia (a progressive form of frontotemporal hair loss associated with local scarring)
    • Central centrifugal cicatricial alopecia
      • Alopecia that starts at the crown and spreads outwards
      • Occurs almost exclusively in black women > 50 years
    • Skin conditions causing scarring alopecia; : ichthyosis, dyskeratosis, discoid lupus erythematosus
    • Acquired scarring alopecia (e.g., via viral diseases, mycoses, burns, chemical burns)
  • Nonscarring alopecia

Diagnosis

The diagnosis is often clear from the patient history and physical examination; however, there are several tests that allow confirmation of diagnosis.

  • 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: performed on hair follicles and shaft to determine the phase of hair growth (anagen, telogen) and structural abnormalities of the shaft
  • Scalp biopsies (performed from sites of active disease): to confirm the diagnosis of cicatricial alopecia
  • Trichograms: aids diagnosis and prognosis of nonscarring alopecia

References:[1][2][3][4][5][6][7]

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 which lead to fragile hair that 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

Features and treatment of androgenetic alopecia in men and women
Men (male pattern baldness) 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
Diagnosis
Treatment
  • First-line treatments
  • 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.

Telogen effluvium

Anagen effluvium

References:[9][10][11][12][13][14][15][16][17][18][19][20][21]

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
  • 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, causes 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

  • Definition: Hair loss in well demarcated patches due to immune-mediated inflammation of hair follicles
  • Epidemiology
  • Etiology
  • Clinical features
    • Abrupt onset (within weeks)
    • Smooth, circular, well defined patches of hair loss without scarring
    • Exclamation point hairs
    • Various patterns of distribution
      • Ophiasis: hair loss localized to the back and sides of the scalp
      • Sisiapho: sparing of the sides and back of the scalp
      • Extensive alopecia areata: hair loss affecting > 50% of the scalp
      • Alopecia universalis : All hair-bearing sites are affected (mimics telogen effluvium).
      • Alopecia totalis: Complete baldness
    • Nail involvement (up to 40% of cases): nail pitting, onycholysis, Beau lines, etc.
    • Other autoimmune disorders may be present (e.g., vitiligo, autoimmune disorders of the thryoid, etc.)
  • Diagnostics
    • Usually clinical diagnosis
    • Biopsy, histology, and trichogram may be performed to confirm the diagnosis
  • Differential diagnosis
  • Treatment
    • Intralesional steroids (triamcinolone)
    • Topical immunotherapy (DCP (diphenylcyclopropenone) or SADBE (squaric acid dibutyl ester)
    • PUVA treatment (Psoralen + UVA)
  • Prognosis: poor for alopecia universalis and totalis

Traction alopecia

  • Definition: 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

References:[21][22][23][24][25][26][27]

  1. Van Beek N, Bodó E, Kromminga A, et al. Thyroid Hormones Directly Alter Human Hair Follicle Functions: Anagen Prolongation and Stimulation of Both Hair Matrix Keratinocyte Proliferation and Hair Pigmentation. The Journal of Clinical Endocrinology & Metabolism. 2008; 93 (11): p.4381-4388. doi: 10.1210/jc.2008-0283 . | Open in Read by QxMD
  2. James WD, Berger T, Elston D. Andrews' Diseases of the Skin: Clinical Dermatology. Elsevier Health Sciences ; 2015
  3. Defects of the hair shaft. http://www.dermnetnz.org/topics/defects-of-the-hair-shaft. . Accessed: May 27, 2017.
  4. Springer K. Common hair loss disorders. Am Fam Physician. 2003; 68 (1): p.93-102.
  5. Female Pattern Baldness. http://www.hairscientists.org/hair-loss-conditions/androgen-related/female-pattern-baldness. . Accessed: May 29, 2017.
  6. Bergfeld W, Hordinsky M, Ofori AO. Telogen Effluvium. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/telogen-effluvium.Last updated: June 22, 2015. Accessed: May 29, 2017.
  7. Donovan J, Goldstein BG, Goldstein AO, Hordinsky M, Ofori AO. Treatment of Androgenetic Alopecia in Men. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-androgenetic-alopecia-in-men.Last updated: February 7, 2017. Accessed: May 29, 2017.
  8. McMichael A, Hordinsky M, Ofori AO. Female Pattern Hair Loss (Androgenetic Alopecia in Women): Treatment and Prognosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/female-pattern-hair-loss-androgenetic-alopecia-in-women-treatment-and-prognosis.Last updated: July 20, 2017. Accessed: July 26, 2017.
  9. Donovan J, Goldstein BG, Goldstein AO, Hordinsky M, Ofori AO. Androgenetic Alopecia in Men: Pathogenesis, Clinical Features, and Diagnosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/androgenetic-alopecia-in-men-pathogenesis-clinical-features-and-diagnosis.Last updated: January 19, 2017. Accessed: May 29, 2017.
  10. Pal L. Polycystic Ovary Syndrome: Current and Emerging Concepts. Springer Science & Business Media ; 2013
  11. Male pattern hair loss . http://www.dermnetnz.org/topics/male-pattern-hair-loss/. Updated: July 1, 2015. Accessed: June 19, 2017.
  12. Olszewska M, Warszawik O, Rakowska A, Słowińska M, Rudnicka L. Methods of hair loss evaluation in patients with endocrine disorders.. 61. 2010; 4 (406-11).
  13. Guo EL, Katta R. Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatol Pract Concept. 2017; 7 (1): p.1-10. doi: 10.5826/dpc.0701a01 . | Open in Read by QxMD
  14. Phillips TG, Slomiany WP, Allison R. Hair Loss: Common Causes and Treatment.. Am Fam Physician. 2017; 96 (6): p.371-378.
  15. Sotiriadis DK. Hair and Nail Disorders of Childhood. Expert Rev Dermatol. 2008; 3 (6): p.677-690.
  16. Messenger AG, Dellavalle RP, Hordinsky M, Ofori AO. Clinical Manifestations and Diagnosis of Alopecia Areata. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. http://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-alopecia-areata.Last updated: February 8, 2017. Accessed: May 29, 2017.
  17. Mounsey AL, Reed SW. Diagnosing and Treating Hair Loss. Am Fam Physician. 2009; 80 (4): p.356-362.
  18. Messenger AG, Dellavalle RP, Hordinsky M, Ofori AO. Management of Alopecia Areata. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/management-of-alopecia-areata.Last updated: December 23, 2016. Accessed: May 29, 2017.
  19. Khumalo NP, Mirmirani P, Hordinsky M, Ofori AO. Traction Alopecia. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/traction-alopecia.Last updated: May 13, 2016. Accessed: May 29, 2017.
  20. Amin S, Sachdeva S. Alopecia areata: A review. Journal of the Saudi Society of Dermatology & Dermatologic Surgery. 2013; 17 (2): p.37-45.
  21. Hair loss and its management in children. http://www.medscape.com/viewarticle/753720_6. Updated: January 1, 2011. Accessed: May 27, 2017.
  22. Alopecia (Hair Loss; Baldness). http://www.msdmanuals.com/professional/dermatologic-disorders/hair-disorders/alopecia. Updated: June 1, 2016. Accessed: May 27, 2017.
  23. Landis MN, Fowler J, Corona R. Keratosis Pilaris Atrophicans. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/keratosis-pilaris-atrophicans.Last updated: October 4, 2016. Accessed: May 27, 2017.
  24. Sperling LC, Hordinsky M, Ofori AO. Central Centrifugal Cicatricial Alopecia. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/central-centrifugal-cicatricial-alopecia.Last updated: June 6, 2016. Accessed: May 27, 2017.
  25. Shapiro J, Otberg N, Hordinsky M, Callen J, Ofori AO. Evaluation and Diagnosis of Hair Loss. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/evaluation-and-diagnosis-of-hair-loss.Last updated: May 23, 2017. Accessed: May 27, 2017.
  26. Blume-Peytavi U, Blumeyer A, Tosti A et al . S1 Guideline for Diagnostic Evaluation in Androgenetic Alopecia in Men, Women and Adolescents. The British Journal of Dermatology. 2011; 164 (1): p.5-15.
  27. Stevenson RE, Hall JG. Human Malformations and Related Anomalies. Oxford University Press ; 2005