[Scarring alopecias].

The irreversibility and the possible important cosmetic consequences of scarring alopecia demand special diagnostic attention in order to promptly attain a precise diagnosis and specific treatment. Scarring alopecias are either due to permanent damage to essential parts of the hair follicle or destruction of the entire hair follicle. They are classified into the categories of primary scarring alopecias, where the hair follicle is the primary target of destruction, and secondary scarring alopecias, where the follicular damage results incidentally from events around impinging on the follicular unit. The differential diagnosis of the more common primary scarring alopecias, e.g. follicular lichen planus, chronic cutaneous lupus erythematosus and folliculitis decalvans, can be difficult when based only on anamnestic and clinical findings. The scalp biopsy is essential for appropriate nosologic classification and has prognostic relevance. The primary therapeutic goal is to halt progression of the irreversible process as early as possible by means of immunomodulatory, immunosuppressive or antiinfectious agents, respectively.