Erdheim-Chester disease with multisystem involvement in a 4-year-old.

Erdheim-Chester disease is a rare form of non-Langerhans histiocytosis of unknown origin occurring mainly in adults. It is extremely rare in children. We report a case of a 4-year-old boy with Erdheim-Chester disease that initially presented as hemifacial palsy and bone pain with multisystem involvement. We describe radiographic findings of bones that show characteristic bilateral symmetrical osteosclerosis with atypical osteolytic lesions in addition to CT findings for pulmonary involvement and MR findings for intracranial lesions.