Professor Gadner has had a keen interest in the histiocytoses, a heterogeneous group of extremely rare and poorly understood diseases of the monocyte-macrophage system since the early 1980’s. In 1983, together with colleagues from other European countries, he initiated the first multicenter prospective standardised protocol for treatment of disseminated Langerhans Cell Histiocytosis (LCH). Gadner became a driving force in increasing international cooperation in the field of LCH, and subsequently was appointed to chair the first randomized international clinical trial LCH-I.

More than 3,000 LCH Patients have been enrolled onto one of the LCH studies. The LCH-study Reference Center in Vienna, is acknowledged worldwide as leading the expertise in treating LCH and continually improving LCH therapy options. The work for the next study, LCH IV is in progress and Gadner will be a Senior Advisor.