Varieties of scarring alopecia

Scarring alopecia (cicatricial alopecia) is a type of hair loss in which hair follicles are permanently destroyed. A wide range of pathologies can cause loss of hair follicles and it is important to realise that scarring alopecia is a clinicopathological reaction pattern and not a diagnosis in itself. Broadly speaking, scarring alopecias can be divided into those forms in which the hair follicle is targeted by an inflammatory infiltrate, or occasionally a neoplastic infiltrate, and those in which follicular destruction is secondary to a general scarring process in the skin caused, for example, by trauma, infection or ionising radiation. This article is devoted to the first of these categories. All forms of scarring alopecias are uncommon and little is known of the underlying pathological mechanisms. Their classification is also the subject of controversy and these difficulties are compounded by the inadequacies of treatment.