Introduction

Langerhans cell histiocytosis (LCH), although considered a benign and treatable condition, can result in sequelae in the various tissues involved. Some of the problems, such as diabetes insipidus (DI), can arise at the time of diagnosis of LCH or even before. It has therefore been suggested that the term ‘permanent consequences’ might be better than the term ‘late effects’ when describing these disabilities (Gadner et al., 1994).

It was recognized decades ago that up to half the survivors of LCH may have residual disabilities which impact on the quality of survival (Komp et al., 1980; Komp, 1980). There have since been reports from single institutions and from co-operative national groups describing long-term complications in LCH patients (Sims, 1977; Ceci et al., 1993; Gadner et al., 1994; French LCH Study Group, 1996; Willis et al., 1996; Haupt et al., 2004). However, there are considerable differences in the reported incidence and prevalence of sequelae, ranging from 20% to 70%, in the various studies. This discrepancy may be due to several different factors including the study size, selection of patient cohorts, treatments used, definitions for diagnosis of sequelae, referral bias to institutions and methods used for follow-up assessment (telephone interviews, questionnaire-based studies and clinical examination) (Table 14.1).

Most of the published literature on permanent consequences are follow-up studies in subjects who had LCH during childhood.