alopecias

Alopecias are disorders characterized by hair loss from the scalp or other hair-bearing areas. They range from thinning to patchy loss or complete baldness and can be temporary or permanent. The causes span genetic, autoimmune, inflammatory, infectious, traumatic, and metabolic factors.

Most alopecias are divided into non-scarring (non-destructive to follicles) and scarring (cicatricial) forms. Non-scarring conditions may allow regrowth, while scarring types involve destruction of hair follicles and often permanent hair loss.

Non-scarring alopecias include androgenetic alopecia (gradual thinning with hormonal influence), alopecia areata (sudden patchy hair loss), telogen effluvium (diffuse shedding after stress or illness), and traction alopecia (hair loss from prolonged tension).

Scarring alopecias (cicatricial) involve inflammatory destruction of follicles, causing permanent hair loss. Examples include lichen planopilaris, discoid lupus erythematosus, frontal fibrosing alopecia, and central centrifugal cicatricial alopecia.

Diagnosis combines history, exam, and tests such as hair pull test, dermoscopy, and scalp biopsy. Other causes—fungal infections, thyroid disease, nutritional deficiencies, or medications—may mimic or accompany alopecia.

Management depends on type. Non-scarring alopecias often respond to topical agents and by treating underlying triggers; alopecia areata may require steroids or other immunomodulators; androgenetic alopecia in men may involve finasteride. Traction alopecia improves with changes in hairstyle. Scarring alopecias require anti-inflammatory or immunosuppressive therapy to limit progression; regrowth is variable. Cosmetic options, including wigs, are commonly used.