Adults with LCH--orphans with an orphan disease.

In the 1950s, Dr Sidney Farber (a clinician) and Dr Louis Lichtenstein (a pathologist) were the first to appreciate that three clinical entities – eosinophilic granuloma, Hand–Schüller–Christian disease and Letterer–Siwe disease – were variants of a single pathological process. Lichtenstein noted close histological similarity between them and coined the all-embracing term ‘Histiocytosis X’. The term ‘Langerhans cell histiocytosis’ (LCH) was adopted by the Histiocyte Society in 1989, after it had been shown that Langerhans-like cells are essential to confirm the diagnosis. The majority of early clinical and pathological observations were made from childhood cases, yet LCH is also commonly diagnosed during adult life.1 Progress in treatment for children with LCH has rapidly moved forward with multi-national randomised trials and increasing awareness of LCHrelated problems in later life.2 Coordinated care for affected adults, however, has lagged behind causing adults with LCH to be described as ‘orphans with an orphan disease’. The conference’s aim was to highlight and address current deficiencies in the hope and expectation that: • LCH in adults will be ‘de-orphanised’ • more adult investigators will become interested in studying this scientifically intriguing and clinically challenging condition.