Investigation of the Hair Follicle Inner Root Sheath in Scarring and Non-Scarring Alopecia

The study investigated the inner root sheath (IRS) in both scarring and non-scarring alopecia by examining 43 cases of alopecia and 15 normal controls. It found that premature desquamation of the IRS, previously thought to be a defining feature of central centrifugal cicatricial alopecia (CCCA), was also present in other types of scarring alopecia. Specifically, the IRS was present at the level of the arrector pili muscle/sebaceous gland/sweat gland coil in 97.9% of alopecia areata, 87.4% of androgenetic alopecia, 59.3% of CCCA, and 49.4% of other scarring alopecia follicles. The study concluded that IRS premature desquamation is a non-specific histologic feature in scarring alopecia and cannot be used alone to define CCCA.