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AT-A-GLANCE
Scarring alopecia occurs in a heterogeneous etiologic group of various disorders.
The inflammatory process leads to permanent destruction of hair follicular stem cell structure and subsequent replacement with fibrous tissue.
The destructive process can occur as a primary or secondary cicatricial alopecia.
Loss of hair-producing attribute finalizes this process and results clinically in permanent alopecia.
No evidence-based treatment is available.
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Cicatricial or scarring alopecias comprise a diverse group of scalp disorders that result in permanent hair loss (Fig. 88-1). The destructive process can occur as a primary or secondary cicatricial alopecia. Primary cicatricial alopecia refers to a group of idiopathic inflammatory diseases, characterized by a folliculocentric inflammatory process that ultimately destroys the hair follicle. Secondary cicatricial alopecias can be caused by almost any cutaneous inflammatory process of the scalp skin or by physical trauma, which injures the skin and skin appendages. Regardless of whether a cicatricial alopecia is primary or secondary in nature, all scarring alopecias are characterized clinically by a loss of follicular ostia and pathologically by a replacement of hair follicles with fibrous tissue.
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Cicatricial alopecias are psychosocially distressing for the affected patient and medico-surgically challenging for the treating physician.
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PRIMARY CICATRICIAL ALOPECIAS
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Inflammatory cicatricial alopecias are rare skin diseases. The epidemiology is basically unknown.
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Table 88-1 outlines the classification of primary cicatricial alopecias1.
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ETIOLOGY AND PATHOGENESIS
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Little is known about most of the etiologies. Hence the exact mechanisms that cause follicle stem cell destruction are not completely understood, and there is no cure as of this writing. Primary cicatricial alopecias are characterized by an inflammatory infiltrate affecting the upper, permanent portion of the follicle referred to as the infundibulum, and below it, the isthmus of the follicle. The isthmus is the home of pluripotent hair stem cells, which are found in the bulge region where the arrector pili muscle attaches to the outer root sheath. Pluripotent hair follicle stem cells are responsible for the renewal of the upper part of the hair follicle and sebaceous glands, and for the restoration of the lower cyclical component of the follicles at the onset of a new ...