The histopathology of primary cicatricial alopecia

Alopecia typically is divided into cicatricial (scarring) and noncicatricial (nonscarring) forms. "Scarring" alopecia implies that follicular epithelium has been replaced by connective tissue and is therefore an irreversible process. In contrast, nonscarring alopecia is potentially reversible as follicular epithelia remain intact. Classification of cicatricial alopecia can be confusing and controversial as most disorders demonstrate overlapping clinical and histologic features. Herein, we present an overview of the histologic assessment of cicatricial alopecia, including an algorithmic approach to the evaluation of biopsy specimens from patients with scarring alopecia.