Histopathologic diagnosis of pityriasis lichenoides et varioliformis acuta and its clinical correlation.

To assess the specificity of the histopathologic features in the diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA), we reviewed the clinical manifestations and courses of 42 patients for whom this diagnosis was suggested in the pathology report. The histologic diagnosis of PLEVA was clinically substantiated in 16 of these 42 cases. Of the 26 cases in which PLEVA was erroneously diagnosed histologically, the correct clinical diagnosis was suggested before biopsies were done in 21 instances. In the five remaining cases, both the prebiopsy clinical diagnosis and the pathologic diagnosis proved to be incorrect. Pityriasis rosea, insect bites, and eczematous dermatitis accounted for the majority of the cases that histologically mimicked PLEVA. The constellation of histologic findings described in PLEVA (presence of intraepidermal lymphocytes and erythrocytes, dermal hemorrhage, and so-called lymphocytic vasculitis) is not specific and may be seen in a variety of dermatologic disorders.