Evaluating the role of therapy in histiocytosis-X. Clinical studies, staging, and scoring

Histiocytosis-X is a difficult disease on which to perform clinical studies. It is a rare disease, with great clinical heterogeneity. The natural history is characterized by periods of spontaneous disease stabilization, remission, and exacerbation. Clinical care is given by several diverse types of physicians. Several suggestions are made for the optimal design and performance of clinical studies aimed at evaluating potentially new therapies, including the proper identification and use of controls. In addition, a staging system is described, and a comprehensive scoring system is given. This scoring system will allow accurate determination of disease activity, and permit analysis of the clinical effectiveness of any new treatment.