Case of Erdheim–Chester presenting with xanthelasma-like eruption and osteolytic bone lesions: A case report

Erdheim–Chester disease is a rare multisystemic non-Langerhans cell histiocytosis presenting 95% with skeletal lesions. Erdheim–Chester disease is due to mutations in the RAS-MEK-ERK pathway where 50% are due to BRAF-V600E mutations. Typical histopathological, clinical, and radiologic features are necessary for the diagnosis of Erdheim–Chester disease. Prognosis depends on the extent of the systemic involvement, and central nervous system involvement has a poorer outcome. We present a 30-year-old Moroccan woman with diabetes insipidus, bone marrow, and asymmetrical axial osteolytic bone lesions. Biopsies were consistent with Erdheim–Chester disease. Despite no treatment, the patient has demonstrated clinical improvement.