SCARRING ALOPECIA - ASPECTS OF CLASSIFICA TION, DIFFERENTIAL-DIAGNOSIS AND PATHOBIOLOGY

Numerous different diseases lead to scarring alopecia with irreversibl e follicular destruction as a common ending. Current classifications a re based on clinical,histopathological or prognostic parameters, as we ll as on pathogenetic criteria which allow only a rough assessment bec ause the precise mechanisms leading to scarring alopecia are still unk nown. Inadequacies of the established classifications are obvious when regarding special forms of scarring alopecia like lichen planopilaris or pseudopelade Brocq. In order to develop more satisfying classifica tions, recent insights into biology and pathology of the hair follicle and follicular cycling have to be considered.The most important struc tures for the survival of the hair follicle are the epithelial stem ce lls which reside in the follicular bulge and the fibroblasts of the de rmal papilla including the molecular communication between these two c ell populations. Research in the field of scarring alopecia should aim at defining the pathological processes on any of the above mentioned levels which will lead to an irreversible damage of the hair follicle thus allowing the development of new therapeutic agents.