The term “scarring alopecia” refers to a diverse group of rare disorders that destroy the hair follicle, replace it with scar tissue, and cause permanent hair loss.
There are several different types of scarring alopecia, generally classified as primary or secondary. In primary scarring alopecia, the hair follicle is the target of the destructive inflammatory process. In secondary cicatricial alopecia, destruction of the hair follicle is incidental to a non-follicle-directed process or external injury, such as severe infections, burns, radiation, or tumors.
Primary scarring alopecia is currently classified by the type of inflammatory cells seen on a scalp biopsy. The inflammatory cells may be primarily lymphocytes, neutrophils, or sometimes the inflammation has mixed cells.
The clinical course is highly variable and unpredictable. Hair loss may be slowly progressive over many years, without symptoms, and unnoticed for long periods. Or the hair loss may be rapidly destructive within months and associated with severe itching, pain and burning. The inflammation that destroys the follicle is below the skin surface and there is usually no “scar” seen on the scalp. Affected areas of the scalp may show little signs of inflammation, or have redness, scaling, increased or decreased pigmentation, pustules, or draining sinuses. Scarring alopecia occurs in otherwise healthy men and women of all ages, is not contagious, not hereditary and is seen worldwide.