Grants Awarded

International Rare Histiocytic Disorders Registry

Principal Investigator
Oussama Abla MD
The Hospital for Sick Children – Toronto, Ontario, Canada

Date of Award
December 2011

Amount of Award

Layperson Summary
The rare histiocytic disorders (RHD), also known as the non-Langerhans cell histiocytoses, are a diverse group of disorders characterized by the accumulation of histiocytes that do not meet the citeria for LCH or HLH. Most of them arise either from a dendritic cell or macrophage cell line. Clinically, they range from localized involvement that resolves spontaneously to progressive disseminated forms that can be life-threatening. The RHD include Juvenile Xanthogranuloma, Erdheim-Chester disease, Multicentric reticulohistiocytosis, Rosai-Dorfman disease and the malignant histiocytoses. Due to the rarity, there is limited data regarding their etiology, treatment and outcome. In fact, members of the Histiocyte society are frequently consulted by colleagues, patients and parents of children with RHD regarding therapeutic options for these rare disorders. Very often, no specific recommendation can be made due to the lack of prospective outcome data. The creation of an international histiocytic disorder registry (IRHDR) could facilitate a uniform diagnosis of the RHD’s, as well as the collection of clinical, treatment and survival data of RHD patients. An expert pathology review will be an essential part of the registry, as it may improve the scientific categorization of histiocytic lesions and the understanding of their distinguishing features. Lastly, a de-identified link between clinical data and companion biology studies can be accomplished through the IRHDR, which may further help in understanding the etiology of these rare diseases as well as identifying potential therapeutic targets. The ultimate goal is to develop treatment guidelines for the rare histiocytic disorders through this international collaborative initiative of the Histiocyte Society.

Twelve Month Report