PT - JOURNAL ARTICLE AU - Sofia Costa AU - Maria José Julião AU - Sónia Silva AU - Manuel João Brito TI - Erdheim-Chester disease: a rare non-Langerhans histiocytosis AID - 10.1136/bcr-2020-241143 DP - 2021 Sep 01 TA - BMJ Case Reports PG - e241143 VI - 14 IP - 9 4099 - http://casereports.bmj.com/content/14/9/e241143.short 4100 - http://casereports.bmj.com/content/14/9/e241143.full SO - BMJ Case Reports2021 Sep 01; 14 AB - A 3-year-old girl was admitted to our hospital with diabetes insipidus and a left eye proptosis. During investigation of diabetes insipidus, an extensive osteolytic mass, involving skull base and maxillo-facial bones, was revealed. Biopsy exhibited dense infiltrate of foamy histiocytes, which were positive for CD68 and CD163 and negative for CD1a and S100 confirming histopathological diagnosis of Erdheim-Chester disease. Treatment with dabrafenib was initiated, with good response and no side effects.