Incidence and clinical features of Langerhans cell histiocytosis in the UK and Ireland

Objectives: There are few published studies on the epidemiology of Langerhans cell histiocytosis (LCH). We undertook a survey to ascertain all newly diagnosed cases aged 0-16 years in the UK and Republic of Ireland. Design: Three methods of ascertainment were used: the British Paediatric Surveillance Unit (BPSU) system, a survey by Newcastle University, and the Children's Cancer and Leukaemia Group (CCLG) registry. Deaths data were obtained from the UK Office for National Statistics and the Central Statistics Office in Ireland. Clinicians who reported cases were sent a questionnaire to obtain demographic and clinical details. Results: Over the 2-year period, 94 cases were identified. The age-standardised incidence rate of LCH in children aged 0-14 years was 4.1 per million per year. The sex ratio (M: F) was 1.5:1 and the median age at diagnosis was 5.9 years. Single system disease (predominantly bony involvement) accounted for 73% of cases and 27% had multisystem disease of whom 7% had involvement of risk organs'' (liver, lung, spleen and bone marrow). Three children died, two of whom were diagnosed after death. Conclusions: This is the first study of LCH to use an active surveillance method with additional sources of ascertainment. Our incidence is comparable with those in other national reports, although it is likely to be an underestimate as each method may have missed some cases, either diagnosed or undiagnosed.