Violaceous, Polygonal Plaques on the Upper Extremities and Trunk

January 03, 2002

Discussion

Lichen planus is a papulosquamous disease of uncertain etiology. The exact prevalence is unknown; however, estimates of slightly less than 1% of the population have been reported worldwide.[1,2] Some studies have demonstrated a female predominance, though others have refuted this finding. No racial predilection has been reported. Peak incidence is in the fourth to sixth decade, with relative rarity at extremes of age.

Lichen planus affects the skin and mucous membranes. Classic cutaneous lesions appear as violaceous, flat-topped, polygonal papules that can coalesce into plaques. A thin, adherent scale may be noted. Close inspection of well-developed lesions may reveal fine, white, reticulated networks known as Wickham's striae.[3] Involvement of the flexural areas of the extremities is common, though the trunk and neck may also be affected. In generalized cases, extensive spread occurs, usually within 1-4 months of onset. Isomorphism (Koebnerization) is well recognized in lichen planus. Pruritus is often present and can be intense.

In the mucosa, lichen planus can assume a variety of forms. It is most commonly seen as fine, white, lacy or reticular patterns on the buccal surfaces. Oral lesions occur in 60% to 70% of patients, and may be the sole manifestation in approximately 25% of those presenting to a general dermatology clinic.[4,5] Erosive oral lichen planus often produces a painful, burning sensation that can cause significant distress. Involvement of the genitalia is not uncommon. Lichen planus of the nails may produce trachonychia, pterygium, and permanent nail loss.

While the cause of lichen planus has remained obscure, various associations have been described. Oral lichenoid reactions have been described in proximity to amalgam dental fillings, and select patients have improved following removal of this material.[6] Patch testing has revealed a significant increase in positive reactions to mercury, gold, and other metals, especially in those with oral disease.[7] Lichen planus has been described following other exposures to gold, such as that following ingestion of liquor containing gold leaf.[8]

The patient's laboratory evidence of chronic HCV infection is interesting. In the past, case reports associated chronic HCV infection with the development of lichen planus.[9] Several studies performed subsequently have supported this association,[10,11,12] particularly in patients with oral lesions, while others refuted it.[13,14,15] Indeed, the high prevalence of HCV infection in the general population and the varying sensitivity of laboratory methods complicate the analysis. Recent editorials continue to demonstrate the controversy surrounding this association.[16]

The polymorphic nature of lichen planus is reflected in the clinical course and subsequently in the selection of therapy. Spontaneous remissions and exacerbations are the rule. Remissions occurred at an average of 15 months in 1 large study, with generalized eruptions, such as those described in our patient, demonstrating more rapid resolution.[4] Recurrence occurs in approximately one quarter of all patients. Isolated oral involvement is predictive of a protracted course.

A variety of therapeutic modalities can be employed, including topical, intralesional, and systemic glucocorticoids, systemic retinoids, psoralen and ultraviolet light A (PUVA), and topical and systemic immunosuppressive agents. Prednisolone is preferred over prednisone for those with compromised liver function. Cyclosporine mouth rinse has been successful for recalcitrant oral lesions.[17] It is interesting that low-dose, low-molecular-weight heparin (3 mg subcutaneously per week) was reported successful in a series of 10 patients.[18] Spontaneous remission often complicates reports of therapeutic success.

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