The epidemiology of Langerhans cell histiocytosis.

Little progress has been made in finding the causes of LCH. Epidemiologic studies are difficult because of the rarity of this disease. Although several associations have been demonstrated in case-control studies, particularly that with thyroid disease, no causal relationships have been documented. Additional case-control studies may uncover the to-date missing lead that may prove fruitful for epidemiologic investigation.