Multiple system Erdheim-Chester disease with massive hypothalamic-sellar involvement and hypopituitarism.

Erdheim-Chester disease (ECD) is a rare multiple system histiocytosis that is characterized pathologically by xanthogranulomatous infiltrates and radiologically by symmetrical sclerosis of long bones. The diagnosis is often confirmed by biopsy of bone or of orbital or retroperitoneal soft tissue. Intracranial involvement is rare.