Lichen planopilaris (LPP), also referred to as follicular lichen planus (LP), lichen follicularis, and lichen planus acuminatus, is characterized by perifollicular erythema and scale that can progress to cicatricial (scarring) alopecia over time. As in lichen planus, LPP is thought to be caused by dysfunction in cell-mediated immunity. In LPP, the immune privilege of the hair follicle bulge is felt to be lost, resulting in loss of hair stem cells after attack by activated T-lymphocytes targeting follicular antigens and an inability of hair to regrow. LPP may present in association with LP, although it is often seen alone. LPP affects women more commonly than men. Those with lighter skin phototypes are more often affected than individuals with darker skin phototypes. The onset of LPP is frequently between age 40 and 60, although the condition has been described in children. LPP is very uncommon in children.

The condition may have an insidious or fulminant onset with hair loss in variable patterns. There are several variants of LPP: classic LPP, frontal fibrosing alopecia, and Graham-Little-Piccardi-Lassueur (Graham-Little) syndrome. Classic LPP presents with follicular violaceous erythema and perifollicular fine scale. Interfollicular erythema may also be seen, and in severe cases, confluent scale may be evident. The perifollicular erythema is usually seen at the periphery of patches of alopecia, which corresponds to active areas of disease. As the disease progresses, permanent cicatricial alopecia or Brocq alopecia occurs. Frontal fibrosing alopecia, as the name implies, clinically appears as a band-like scarring alopecia of the frontal hairline that commonly affects women. Graham-Little syndrome consists of the triad of cicatricial alopecia of the scalp, a lichenoid follicular eruption, and noncicatricial pubic and axillary hair loss. In addition, a diffuse variant was recently described. It presents with diffuse scalp itching with widespread hair thinning and erythema. This variant has no predilection by sex.

Increased hair shedding, severe itching, scaling, burning, and tenderness are common symptoms associated with LPP.

Related topics: oral lichen planus, lichenoid drug eruption