EPIDEMIOLOGIC-STUDY OF LANGERHANS CELL HISTIOCYTOSIS IN CHILDREN

Objective: The etiology and pathogenesis of Langerhans cell histiocyto sis (LCH) remain poorly understood. We conducted an exploratory epidem iologic study to investigate potential risk factors associated with LC H. Study design: We used a case-control study design to Obtain data fr om parents of children with LCH (n = 459) who were members of the Hist iocytosis Association of America and Canada. The two control groups co nsisted of 683 community control subjects and 3719 children with child hood cancers treated at participating Children's Cancer Group institut ions. Results: The median age at diagnosis of LCH was 1.8 years (range 0.1 to 14.6 years). Cases were cetegorized as multisystem LCH (MS-LCH ) (n = 208) and single-system LCH (SS-LCH) (n = 198). Statistically si gnificant associations included the following: infections in the neona tal period (MS-LCH, odds ratio (OR) = 2.2), solvent exposure (SS-LCH, OR = 54.9), childhood vaccinations (MS-LCH and SS-LCH, OR = 0.4), thyr oid disease in the proband (MS-LCH and SS-LCH, OR = 21.6), and family history of thyroid disease (MS-LCH and SS-LCH, OR = 1.4). The associat ion with thyroid disease In the proband was explained partially by the involvement of the pituitary, with the relative risk decreasing when patients with diabetes insipidus and thyroid involvement were excluded from analysis. Conclusions: This large hypothesis-generating study pr ovides directions for future investigations in weal-designed populatio n-based or hospital-based epidemiologic studies.