A clinicopathologic study of scarring alopecia due to lichen planus - Comparison with scarring alopecia in discoid lupus erythematosus and pseudopelade

The clinicohistologic findings in 68 patients with lichen planus scarring a lopecia (LP) were compared with these of 25 patients with discoid lupus ery thematosus of the scalp (DLE) and 25 with pseudopelade (PP). The combinatio n of diffuse scaling, erythema, telangiectases, and mottled hyperpigmentati on within areas of scarring alopecia was a distinctive feature of DLE, wher eas the clinical picture of PP was indistinguishable from that seen in 29 p atients with LP. In most patients with LP, the histologic changes involved only the follicles and the perifollicular dermis. Less frequently, the infl ammatory process extended to the epidermis and the papillary dermis. In all cases, histopathologic features allowed LP to be distinguished from DLE re gardless of the stage of the disease. The finding of a bandlike fibrotic th ickening of the papillary dermis accompanied by fibrotic tracts at sites of destroyed follicles appeared to be a hallmark of "burnt out" lesions of LP . This histologic clue may be helpful in achieving a specific diagnosis of LP in cases that fulfill the clinical criteria for PP.