Lichen Planopilaris

A rare cutaneous variant of lichen planus which affects hair follicles. It may occur on its own or in association with more common forms of lichen planus, usually classical type and/or oral lichen planus.

Epidemiology

The prevalence is unknown. LPP is more frequent in women than in men.

Clinical description

The disease manifests in adulthood (40-60 years of age), with some rare cases in childhood. Patients present with peri-follicular inflammation and hair loss. They may be asymptomatic or have itch or discomfort. The scalp is the commonest area affected but any hair bearing skin may be affected, like for example the axillae or the pubic area. Perifollicular erythema, scales, and/or keratotic plugs are seen at the edge of the affected area. Single or multiple lesions of scarring alopecia lacking follicular orifices are typical. Two other variants of LPP can be observed: frontal fibrosing alopecia (FFA), and Lassueur-Graham-Little syndrome (see these terms). In FFA, there is symmetrical, progressive anterior hairline loss of the scalp associated with eyebrow loss. The Lassueur-Graham-Little syndrome constitutes a combination of lichen planus follicularis of the scalp with follicular keratosis and noncicatricial alopecia of the axillae and pubes.

Etiology

Etiology is unknown but LPP is thought to be an autoimmune disorder in which T-lymphocytes attack and destroy keratinocytes expressing unknown target antigens. Triggering factors could be pharmacologic agents, contact sensitizers or infectious agents.

Diagnostic methods

Diagnosis is based on clinical and histopathological findings. Biopsy of an inflammatory lesion shows a band-like perifollicular lymphocytic infiltrate at the level of the isthmus and infundibulum. There may be vacuolar changes of the basal layer and follicular plugging. In more advanced lesions, perifollicular fibrosis and replacement of hair follicles by fibrosis are found. Diagnosis is difficult in the later stages when inflammation disappears.

Differential diagnosis

Differential diagnosis includes discoid lupus erythematosus (DLE), folliculitis decalvans, mucous membrane pemphigoid (see these terms), seborrheic dermatitis, alopecia areata, and central centrifugal cicatricial alopecia (CCCA).

Management and treatment

There is no long-term effective treatment for LPP. Current treatments aim at slowing down progression of hair loss and reduction of symptoms. Topical, intralesional and oral corticosteroids are the mainstay of treatment. Unfortunately, relapse is common. Other options for treatment include hydroxychloroquinine, ciclosporin and methotrexate.

Prognosis

LPP can progress slowly or rapidly. Some cases may spontaneously resolve but others are progressive.