HUMAN HERPESVIRUS-6 IS PRESENT IN LESIONS OF LANGERHANS CELL HISTIOCYTOSIS

Langerhans cell histiocytosis (LCH) is a disease characterized by Lang erhans cell infiltration of skin and bone, with its most severe form m anifested by multifocal infiltration of many organs. The etiology is u nknown, although viral infection has been proposed as a potential path ogenic factor. Human herpesvirus 6 (HHV-6), a recently described membe r of the human herpesvirus family, has been associated with atypical o r malignant lymphocytic processes, and immune disorders. Based on thes e observations, we suspected that HHV-6 may play a role in the pathoge nesis of LCH. Lesional tissue of 30 patients with LCH was retrospectiv ely examined for the presence of HHV-6 by using the polymerase chain r eaction. Tissue specimens from 63 patients with other benign and malig nant histiocytic and lymphocytic diseases served as controls. In addit ion, all specimens were examined with control primers specific for her pes simplex virus (HSV). HHV-6 DNA was detected in lesions of 14 of 30 patients with LCH (47%).On clinical subgroup analysis, HHV-6 DNA was found in 10 of 16 patients with extraosseous disease (63%) and in four of 14 patients with disease limited to b ne (29%). In each case, the prevalence of HHV-6 in LCH lesions was statistically significant, when compared to the control population. HSV DNA was not found in any of t he LCH or control specimens. Although the presence of a virus alone do es not establish a causal role in the disease it supports the possibil ity of an etiologic relationship. From this study, we emphasize the ne ed for further investigation of the potential HHV-6-mediated pathogene sis of LCH.