[Erdheim-Chester disease: a rare histiocytosis with outstanding response to cobimetinib.].

Introduction: Erdheim-Chester Disease (ECD) is a rare form of histiocytosis, characterized by xanthogranulomatous infiltration of multiple organs by lipid-laden histiocytes. It is considered a myeloid inflammatory clonal disorder that mainly affects men with a mean age of 55 years.

Methods: We present the case of a 65-year-old man who consulted our Endocrinology Unit because of polyuria and polydipsia of 4 months of evolution, diagnosing central diabetes insipidus associated with pituitary infiltration.