Although alopecia areata has been known for many years as a distinct clinical entity offering little difficulty in differential diagnosis, the cause remains unknown, as evidenced by the many case reports suggesting different theories of causation.
Typical alopecia areata may appear at any age, in either sex, and may involve the scalp, eyebrows or bearded region. It usually occurs with a sudden asymptomatic loss of hair, leaving a sharply circumscribed oval or irregular smooth noninflammatory area of almost complete alopecia, containing only a few so-called exclamation point hairs. In rare instances the alopecia may become total. In differential diagnosis, syphilitic "moth-eaten" alopecia, ringworm of the scalp, trichotillomania, folliculitis decalvans, lupus erythematosus, scars and radiation alopecia must be considered, as well as acute local infectious processes.
A patient with the usual case of alopecia areata, with or without treatment, ordinarily shows regrowth of hair in a period of three to six
HAYNES HA, PARRY TL. ALOPECIA AREATA ASSOCIATED WITH REFRACTIVE ERRORS. Arch Derm Syphilol. 1949;59(3):340–343. doi:10.1001/archderm.1949.01520280092012
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