High frequency of Epstein-Barr virus-infected lymphocytes in pilonidal cysts

Circulating memory B cells are considered as the main reservoir for Epstein-Barr virus. Several studies identified the presence of Epstein-Barr virus-infected B cells in the lesions of Crohn disease and ulcerative colitis suggesting that colon mucosa with chronic inflammation could be a potential site of Epstein-Barr virus replication. However, whether skin could be also an Epstein-Barr virus reservoir has not yet been investigated. We used pilonidal cysts as a model of skin chronic inflammation, and we found in 20 (55.6%) of 36 cases variable amounts of Epstein-Barr virus-infected cells as assessed by in situ hybridization using Epstein-Barr virus-encoded RNA probe and immunostainings. Most (95%) of the Epstein-Barr virus-positive cells were of B-cell phenotype, whereas scattered cells were double stained with Epstein-Barr virus-encoded RNA probes and T-cell markers. Epstein-Barr virus-encoded RNA+ cell density correlated with the intensity of inflammation. This density was similar to that observed in chronic diverticulitis but higher when compared with appendicitis, suggesting that chronic rather than acute inflammation facilitates the recruitment of Epstein-Barr virus-infected cells in diseased tissues. Altogether, these data suggest that, in immunocompetent patients, skin inflammatory lesions contain Epstein-Barr virus-infected cells exhibiting latency type I. Moreover, skin-like gastrointestinal mucosa is a potential site of Epstein-Barr virus replication and spreading. Our results may explain the pathogenesis of the Epstein-Barr virus-positive mucocutaneous ulcer.