Histopathological Features in Both the Eschar and Erythematous Lesions of Tsutsugamushi Disease: Identification of CD30+ Cell Infiltration in Tsutsugamushi Disease

Abstract

Tsutsugamushi disease is an acute febrile infectious disease caused by Rickettsia tsutsugamushi. An infection is heralded by the presence of an eschar at the site of the inoculating chigger bite and followed by the development of a disseminated erythematous macular rash. CD30 expression is found in anaplastic large cell lymphoma; however, expression in nonneoplastic cutaneous disorders, such as atopic dermatitis, drug reactions, scabies, and various infectious diseases, has also been reported. Study of the cutaneous histopathology of tsutsugamushi disease has been limited. In this study, we performed biopsies of both the eschar and erythematous lesions of 15 cases of tsutsugamushi disease to assess the histopathological changes including the CD3, CD4, CD20, CD30, and CD68 reactivity. Twelve women and 3 men were included with an age range from 21 to 73 years. The most common location of the eschar was the trunk (53.3%). The histological features showed increased leukocytoclastic vasculitis in the eschar (93.3%) compared with the erythematous lesions (33.3%); basal vacuolar changes were more common in the erythematous (100%) than in the eschar lesions (20%). The inflammatory infiltrate had a majority of CD3- and CD68-positive cells. Seven erythematous lesions and 7 eschar lesions showed atypical cells that were CD30-positive cells. Here, we report on the cutaneous histopathology and pattern of inflammatory infiltrates of tsutsugamushi disease. Leukocytoclastic vasculitis and basal vacuolar changes were the characteristic features of the eschar and the erythematous lesions, respectively. In addition, CD30-positive cell infiltration was identified for the first time in this disease.