Erdheim–Chester disease

Erdheim–Chester disease (ECD) is an extremely rare disease classified as a non-Langerhans-cell histiocytic neoplasm. In 2016, the World Health Organization (WHO) defined ECD as a slow-growing blood cancer that may originate in the bone marrow or precursor cells. Typical onset occurs in middle aged individuals, although pediatric cases have been documented. The exact cause of ECD remains unknown, though it is believed to be linked to an exaggerated TH1 immune response. The disease involves an infiltration of lipid-laden macrophages, multi-nucleated giant cells, an inflammatory infiltrate of lymphocytes and histiocytes in the bone marrow, and a generalized sclerosis of the long bones.

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