Human Herpesvirus-6 DNA and Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a rare histiocytic proliferative disorder of unknown etiology that mainly affects young children. The histological feature is the granuloma-like proliferation of Langerhans-type dendritic cells. The possible role of viruses such as Epstein-Barr virus (EBV, HHV-4), human herpesvirus-6 (HHV-6), herpes simplex virus (HSV) types 1 and 2, and cytomegalovirus (CMV, HHV-5) in the pathogenesis of LCH has been suggested in some studies; however, this still remains under debate. HHV-6 infections are reported to be associated with LCH, but no such reports could be found on Iranian children in the English-language medical literature. This study investigated the presence of HHV-6 in Iranian children with LCH. In this retrospective study, we investigated the presence of HHV-6 DNA in 48 patients with LCH, using paraffin-embedded tissue samples, and in 48 controls (age- and tissue-matched) using the nested polymerase chain reaction (nested PCR) method. The patients had been treated at the Department of Pediatric Pathology from 2002 - 2013 and had undergone operations for reasons other than infectious disease. Only the pathology reports were retrospectively reviewed, and the patients were anonymous. There was no significant difference in the prevalence of HHV-6 detection between the LCH patients and the control subjects. HHV-6 was found by nested PCR in one (2.1%) of the 48 LCH patients and in six (12.5%) of the 48 control cases. P = 0.11 was calculated using Fisher’s exact test (OR: 0.15; 95%CI: 0.02 - 1.29). Our study is the first to investigate patients with LCH and its possible association with HHV-6 in Iran. Considering the P level of 0.11, which is statistically insignificant, our findings fail to support the hypothesis of a possible role for HHV-6 in the pathogenesis of LCH. These results are in concordance with previous investigations showing negative results.