Skin Disorders Guide

Diagnosis Hallmarks

1. Distribution - trunk and extremities, special predilection for the wrists, penis, and mouth
2. Violaceous color
3. Shiny, flat-topped papules
4. Koebner phenomenon
5. Wickham’s striae

Clinical Presentation

The primary lesion of lichen planus is a violaceous, flat-topped papule 2 to 4 mm in diameter. Scale, because it is of lichen type, is often overlooked, the shiny, mirror-like surface of the papules is the only clue to its presence. The papules of lichen planus generally occur in clusters (sometimes taking on an annular configuration), and they frequently coalesce to form small plaques 1 to 2 cm in diameter. Plaques larger than this are only seen in the hypertrophic variant of the disease. Papules may also be arranged in a linear configuration as a result of the Koebner phenomenon. A fine network pattern of gray-white lines (Wickham’s striae) can be noted on the surface of the larger papules.

The lesions of lichen planus can occur anywhere on the body, but the volar surface of the wrists, the anterior surface of the lower legs, and the shaft and glans of the penis are particularly likely to be involved. Striking postinflammatory hyperpigmentation sometimes develops at sites where lesions have resolved. White lacy plaques are quite often present on oral mucous membranes.

Lichen planus is, by far, the most pruritic of the papulosquamous diseases. Surprisingly, this severe itching is not commonly accompanied by scratching to the point of visible excoriations. Lichen planus occurs at any age, but it is particularly common in mid adult life.

Course and Prognosis

Lichen planus is a chronic disease in which new lesions appear as old lesions resolve. Thus, like psoriasis, lichen planus is a disease of constantly changing patterns. A few fortunate patients have attacks that last only a matter of months, but most patients experience many years of (sometimes intermittent) activity. Lichen planus seems to occur more commonly than would be expected in patients with biliary cirrhosis, especially when penicillamine is used in therapy.

Pathogenesis

Lichen planus is a disease of unknown etiology. Several features suggest that it is an autoimmune disease. These include the deposition of immunoreactants such as immunoglobulin M (IgM) and fibrin in the papillary dermis, the concomitant presence of other autoimmune disease in a few patients, and the occurrence of lichen planus-like changes in graft-versus-host reactions.

Clinical experience suggests that stress, particularly in the form of “executive, type A behavior,” is a common and important precipitating factor. Interestingly, hypertension is also found with appreciable frequency in these patients. Lichen planus-type lesions can occur as the result of medication reactions. This pattern is most likely to occur with chlorothiazides, quinidine, benzodiazepines, and quinacrine.

Therapy

Lichen planus is a difficult disease to treat. Topically applied steroids should be tried, but even with occlusion, such therapy is often disappointing. Orally administered steroids can be used to bring an acute flare-up under control, but recrudescence is very likely when the steroids are stopped. Psoralen-long-wavelength ultraviolet light (PUV A) therapy works quite well, but as for psoriasis, prolonged treatment is necessary. Orally administered retinoids are also quite effective, though the usual problems with toxicity limit the appeal of this approach. In some circumstances, psychologic counseling, the administration of tranquilizers, or the use of behavior modification for stress reduction may be beneficial.