Skip to Main Content

For further information, see CMDT PART 6-54: Alopecia

Key Features

Essentials of Diagnosis

Forms of hair loss

  • Scarring (suggested by absent follicular markings)

  • Nonscarring (suggested by present follicular markings)

General Considerations


  • Irreversible and permanent, thus it is important to treat the scarring process as early as possible

  • May occur following

    • Chemical or physical trauma

    • Bacterial or fungal infections

    • Severe herpes zoster

    • Chronic discoid lupus erythematosus

    • Scleroderma

    • Excessive ionizing radiation

  • Specific dermatologic diseases of the scalp that result in scarring alopecia include

    • Lichen planopilaris

    • Frontal fibrosing alopecia

    • Dissecting cellulitis of the scalp

    • Folliculitis decalvans

  • The specific cause is often suggested by

    • The history

    • The distribution of hair loss

    • The appearance of the skin, as in lupus erythematosus


  • May occur in association with various systemic diseases such as

    • Systemic lupus erythematosus

    • Secondary syphilis

    • Hyperthyroidism or hypothyroidism

    • Iron deficiency anemia

    • Vitamin D deficiency

    • Pituitary insufficiency

Androgenetic alopecia

  • Both men and women are affected, often starting in the third decade

Telogen effluvium

  • A transitory increase in the number of hairs in the telogen (resting) phase of the hair growth cycle

  • Causes

    • Spontaneous occurrence

    • Iron deficiency

    • May appear at the termination of pregnancy

    • Precipitated by "crash dieting," high fever, stress from surgery or shock, or malnutrition

    • Provoked by hormonal contraceptives

  • Latent period of 2–4 months

  • The prognosis is generally good

Alopecia areata

  • Unknown cause but is believed to be an immunologic process (autoimmune)

  • Occasionally associated with Hashimoto thyroiditis, pernicious anemia, Addison disease, and vitiligo

Clinical Findings

Symptoms and Signs

Androgenetic alopecia

  • In men, the earliest changes occur at the anterior portions of the calvarium on either side of the "widow's peak" and on the crown (vertex)

  • In women, there is retention of the anterior hairline while there is diffuse thinning of the vertex scalp hair and a widening of the part

  • The extent of hair loss is variable and unpredictable

Alopecia areata

  • Typically, there are patches that are perfectly smooth and without scarring

  • Tiny hairs 2–3 mm in length, called "exclamation hairs," may be seen

  • Telogen hairs are easily dislodged from the periphery of active lesions

  • The beard, brows, and lashes may be involved

  • Involvement may extend to all of the scalp hair (alopecia totalis) or to all scalp and body hair (alopecia universalis)

Differential Diagnosis

  • Scarring (cicatricial)

    • Chemical or physical trauma

    • Lichen planopilaris

    • Bacterial or fungal infection

    • Herpes zoster (shingles) (severe)

    • Discoid lupus erythematosus

    • Scleroderma

    • Excessive ionizing radiation

  • Nonscarring

    • Androgenic (male pattern) ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.