Abstract

Langerhans cell histiocytisis (LCH) is the most common of the histiocytic disorders [39]. It represents a spectrum of several clinical entities chracterized by a disorder of antigenpresenting dendritic cells of the immune system. Its epidemiology is poorly understood and based mainly on a few international and regional studies of defined populations [34]. The overall incidence rate varies from 2.6 to 8.9 children per million per year [1, 19, 34, 36]. Children of any age can be affected, however the peak age of presentation, in children, is between the ages of one and three [34]. LCH is also diagnosed in adults [37] but only a few reports are available describing LCH patients with onset during adulthood [3]. Some studies reveal a greater prevalence of LCH among male children [19]. On the other hand, in adults, a preponderance of females is documented with onset as late as the ninth decade of life [26]. Dissemitaned LCH is described to present most frequently in the first year of life [19]. Congenital self-healing LCH is an uncommon form of LCH, which is usually present at birth or in the neonatal period [23].