Alopecia differential diagnosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Ogechukwu Hannah Nnabude, MD


There is a very wide list of diseases and conditions that can lead to alopecia. Proper history taking and physical examination, along with laboratory, microbiology, and in some cases, imaging studies, are helpful in narrowing down the diagnosis. Alopecia can be caused by many different diseases. Some of the most well known and common causes are: androgenetic alopecia, alopecia areata, telogen effluvium, anagen effluvium, traction alopecia, and trichotillomania. Endocrine disorders such as hypothyroidism, hypoparathyroidism and Cushing's syndrome as well as malnutrition and medications are also possible causes of alopecia.

Differentiating Alopecia from Other Diseases

Disease/Condition Clinical presentation Demographics/History Diagnosis Other notes
Androgenetic Alopecia [1] [2] [3]
  • Male pattern: The frontal hairline is thinner, hair loss occurs at the crown of the scalp, hair recession is seen at the temporal aspects of the scalp; Female pattern: Hair loss occurs at the crown of the scalp, however, the frontal hairline remains preserved.
  • Androgenetic alopecia is believed to have a worldwide prevalence of about 50,000 per 100,000 men and 15,000 per 100,000 women with post-menopausal women making up the majority.
  • Diagnosis is mostly clinical and is based on the pattern and absence of other explanations.
  • Unlike in telogen effluvium, hair pull test shows a less than 20% telogen count.
  • It is the most common cause of hair loss.
Alopecia Areata [1] [4] [5] [6] [3] [7] [8] [9]
  • It presents with round patches of total hair loss with retained follicular ostia with the beard and scalp being the most frequently affected areas.
  • Alopecia areata has a prevalence of 100-200 per 100,000 individuals, and a risk of about 2% over an individual's life. The mean age for diagnosis of alopecia areata is about 32 years in males and 36 years in females.
  • Close observation reveals the characteristic exclamation mark hairs. A hair pull test followed by trichogram shows telogen and pencil point shafts.
Telogen Effluvium [10] [11] [3]
  • There is a massive amount of hair shedding that is triggered by physiologic or psychologic stress.
  • Although considered to be a relatively common condition, the precise prevalence of telogen effluvium remains unknown. However, it is believed that it is more commonly seen in females than in males
  • Hair pull test followed by trichogram reveals numerous clubbed-shaped hairs; telogen count must exceed 20% for diagnosis.
  • It could be an acute self-limiting form triggered by stressors such as crash diets, childbirth, febrile illness, or psychological stress.
  • It may be chronic and present in association with female pattern hair loss.
Anagen Effluvium [1]
  • There is diffuse hair loss and it is characterized by hair breakage that takes place in the anagen phase.
  • Trichoscopy would reveal the characteristic narrowing, fractured hair shafts with an absence of bulbs.


Trichotillomania [12] [13] [14] [15] [16] [1] [17] [18]
  • Presents with uneven broken hairs in the most frequently selected areas which are the scalp, eyebrows, eyelashes, body hair, facial hair, and pubic hair.
  • Based on the limited studies that have been done to determine the prevalence of trichotillomania among U.S. university students, Israeli adolescents, and older adults within the same community, the prevalence was shown to be between 500 per 100,000 to 2000 per 100,000.
  • It usually starts around the age of 12–13 years
  • It is more common in males during the childhood years while it is more common in females in the adult years.
  • Scalp inspection reveals uneven patches of hair loss with broken hairs that remain well attached to the skin.
  • A characteristic finding that distinguishes trichotillomania from alopecia areata is that the affected areas are not totally devoid of hair shafts.
  • It occurs as a result of a lack of impulse control in which an individual pulls on hair.
Traction Alopecia [19] [1] [20] [21] [20]
  • Hair loss at regions of the scalp exposed to tension on hair follicles for a prolonged period of time in people who make tight hairstyles.
  • Traction alopecia is more commonly seen among black populations with females being affected more often than males at a rate of about 31,000-32,000 per 100,000 women compared to about 2,300 per 100,000 men.
  • Traction alopecia is seen in about 18,000 per 100,000 girls between the ages of 5.4 to 14.3 years based on a study of African-American girls.
  • Mostly a clinical diagnosis based on hair loss at areas of the scalp where tension on the hair is highest.
  • Early detection and switching to more loose hairstyles may reverse the condition, however, with prolonged tension on the scalp destruction of the hair follicles will occur, causing the condition to become irreversible.
Chronic Cutaneous Lupus Erythematosus [22] [1]
  • Presents with an area with hair loss that gradually converts into scaly, thickened papules then into poorly-defined, variably-shaped plaques with atrophy, follicular plugging, telangiectasia, and depigmentation.
  • Black populations tend to have more serious disease.
  • Cutaneous lupus erythematosus is more common in males than in females, with a ratio of about 59.4 per 100,000 versus 1.6 per 100,000.


Tinea Capitis [23] [24] [25] [26] [27] [3]
  • Presents in diverse ways such as ordinary scaling without any obvious hair loss which is considered to be a seborrheic form, a crusted or pustular form that may be localized or diffuse, a ‘black dot’ type that is characterized by tiny black dots within regions of alopecia, an inflammatory mass called kerion, and a round, bald, scaly patch where the follicular ostia are filled with keratinous debris.
  • A unique feature of tinea capitas is the presence of post-auricular and cervical lymphadenopathy.
  • It is more common in the pediatric population.
  • Potassium hydroxide preparation can be added to skin scrapings of affected areas in order to diagnose the condition. [1]
  • Wood's light can also be used in diagnosis as majority of Microsporum spp will appear bluish-green, occasionally dull yellow (Microsporum gypseum) and dull blue (Trichophyton schoenleinii).
  • In the U.S., under 5% of cases will show fluorescence.
  • Possible complications of tinea capitas are kerion, an abscess in the scalp, or favus, another inflammatory form in which there is honeycomb destruction of the hair shaft. Both are severe forms of the disease and can cause permanent scarring.

The following lists the complete differential diagnosis of Alopecia:

Non-Scarring Alopecia

Scarring Alopecia



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