An epidemiological survey of Langerhans cell histiocytosis in children in the United Kingdom and Republic of Ireland

Abstract

Langerhans Cell Histiocytosis (LCH) is a rare disease of the immune system which, in children, is treated mainly by oncologists. It has several forms ranging from spontaneously regressing localised bony disease to life-threatening multi-organ failure. Mortality is low but children may be left with long-term sequelae. LCH is inconsistently registered by cancer registries and although the Children‟s Cancer and Leukaemia Group (CCLG) records cases, its incidence in the UK and Republic of Ireland was previously unknown, prompting this national survey to describe the epidemiology of LCH in children. Three sources of case ascertainment were used: the British Paediatric Surveillance Unit, a Newcastle-based postal survey of other clinicians, and the CCLG. National deaths data were also obtained. Questionnaires were sent to reporting clinicians to obtain further information and to follow up cases one and two years after diagnosis. The completeness of ascertainment was estimated by capture-recapture methods; the spectrum of disease was described; possible associations, event-free survival and mortality were assessed. Each source uniquely ascertained cases and completeness was estimated at 93%. 94 children were identified giving an incidence rate, comparable with other European reports, of 4.1 per million per year (aged 0-14 years). 67% of cases had SS bone disease and 26% had multi-system disease. More cases than expected were diagnosed in spring (p=0.04) and there was a higher than expected proportion of mixed/other ethnicity children than in the general population (p=0.027). At the end of the study, 91% had no active disease and 18% had sequelae. Mortality was 3.2%. This is the first national study to use a well-established prospective method of case identification. The importance of multiple sources of ascertainment was demonstrated. Although the data and number of cases were limited, the results above, and other observations, indicate the need for further follow up and larger studies.