Alopecia Areata Differential Diagnoses

Updated: Jun 27, 2023
  • Author: Chantal Bolduc, MD, FRCPC; Chief Editor: Dirk M Elston, MD  more...
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Diagnostic Considerations


Alopecic patches have unusual shapes and sizes and show broken hairs; no inflammation or epidermal change occurs. A scalp biopsy can be helpful if the diagnosis is difficult clinically.

Tinea capitis

The diagnosis is suggested by erythema, scaling, and crusting locally on the scalp.

Scarring alopecia and posttraumatic alopecia

These can be differentiated by the absence of follicular ostia or some degree of atrophy.


Syphilis rarely is seen but should be suspected in patients at high risk or with other signs or symptoms.

Telogen effluvium and androgenetic alopecia

Exclude these when hair loss is diffuse. In androgenetic alopecia, hair loss is patterned and usually is slowly progressive rather than acute. Differentiating telogen effluvium from diffuse alopecia areata is difficult in the absence of an obvious precipitating factor that can result in telogen effluvium. Noting hair loss on other hair-bearing areas can be helpful and favors a diagnosis of alopecia areata.

Differential Diagnoses