BackgroundPermanent consequences (PC) are often described among subjects with Langerhans cell histiocytosis (LCH) but data on the real incidence are scarce. Within the Histiocyte Society (HS), and in order to design a definitive late effects study, a retrospective survey was organized to describe the prevalence of PC among long‐term survivors of LCH.MethodsNine institutions contributed with their LCH patients having a minimum follow‐up of 3 years. Information was collected on their disease‐history, and on type and date of onset of any PC. Because of the retrospective type of this study, it was accepted that each institution might have used different criteria to assess PC.ResultsOne hundred eighty‐two subjects were registered and in 95 (52%) at least 1 PC was reported. For some specific PC (e.g., anterior pituitary dysfunction) information was too scarce to provide reliable data. PC were more frequent among subjects with multisystem (MS) disease (71%), compared to those with single system (SS) disease (24%); P < 0.0001. The most frequently reported PC were diabetes insipidus (DI) (24%) orthopedic abnormalities (20%), hearing loss (13%), and neurological consequences (11.0%). Analysis of cumulative risk showed that some types of PC may become manifest more than 10 years from diagnosis.ConclusionsThis survey on selected cases of LCH survivors has confirmed that late sequels are frequent, and that they are even more common among those with MS LCH. Our findings highlight the need for long‐term and patient‐oriented follow‐up in children with LCH. © 2004 Wiley‐Liss, Inc.

Ten (24%) of the 41 patients had abnormal findings on radiological examination of the lungs at long-term follow-up and seven are or had been smokers. It is of great importance that patients with LCH be informed about smoking-related pulmonary morbidity. Prolonged monitoring of the lungs for smokers and patients with known pulmonary involvement is recommended.

Multi-system LCH is associated not only with increased mortality but also pronounced propensity for severe late sequelae; 51% of the patients (multi-system=33%, single-system=67%) were alive without sequelae at follow-up. Among multi-system patients, at least 19% suffered CNS sequelae.