Human Herpesvirus-6 DNA and Langerhans Cell Histiocytosis

Background: 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. Objectives: 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. Methods: 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. Results: 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). Conclusions: 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.