A clinical and histopathologic study of lichen nitidus

Background: Lichen nitidus is a rare condition of unknown cause, characterized by minute, flesh-colored, shiny papules occurring on the abdomen, chest, extremities, and genitalia. There have been few studies worldwide about the clinical and histopathologic manifestations of lichen nitidus. Objective: The purposes of this study were aimed to evaluate the clinical and pathologic presentations of lichen nitidus. Methods: The medical records and histopathological slides of 31 patients with lichen nitidus diagnosed at Korea University Medical Center from April 1983 to March 2002 were reviewed. Results: 1) Onset age of skin lesions ranged from 1 year to 34 years and 17 cases(63%) were developed in the patients younger than 9 years old. The ratio of male to female was 2.1:1 and the mean duration of the eruption was 2.8 years. 2) Twenty four cases(77%) had multifocal lesions, four cases(13%) had generalized lesions, and three cases(10%) had unifocal lesions. The predilection sites were trunk(27.8%), upper extremities(24.1%), lower extremities(19%), face and neck(13.9%), penis(10.1%), and hands(5.1%) in decreasing order. 3) Mild pruritus was noted in 8 cases(26%), and Koebner phenomenon in 9 cases(29%). 4) Atopic dermatitis was noted in 3 cases(10%), lichen planus in 1 case, urticaria in 1 case, and verruca plana in 1 case. None had a positive family history. 5) The papules were closely grouped but remained discrete except in areas exhibiting the Koebner phenomenon. The color of papules was skin-colored(74%), reddish-brown(13%), and mixed(13%). 6) The frequent histopathologic findings were liquefaction degeneration of the basal layer(100%), edema of the dermis within the areas of the infiltrate(100%), clawlike rete ridges(96.8%), epidermal atrophy(87.1%), perivascular inflammatory cell infiltrate(87.1%), and absent or thinned granular layer(77.4%). 7) We divided lichen nitidus into three stages, early stage, developed stage and late stage, according to the predominant cell types of the inflammatory infiltrates in the dermal papilla. There was a tendency of increasing number of infiltrated dermal papillae as the lesion progressed to late stage. It was interpreted as the lesions tend to be grouped clinically. Conclusion: In our study, we were able to obtain the clinical and histopathological features of lichen nitidus which help to understand lichen nitidus.