FDG-PET in the Erdheim-Chester disease: its diagnostic and follow-up role.

A 62-year-old man presented with diabetes insipidus, pulmonary fibrosis, right atrial tumor and bilateral knee osteoarthritis with cystic lesions of distal femur and proximal tibia. Scintigraphy and histological examination of right femur bone biopsy revealed changes characterized for Paget's disease. Re-evaluation of the computer tomography (CT) scans and histological samples revealed diffuse infiltrates of foamy histiocytes in the bone marrow what was consistent with Erdheim-Chester disease. Positron emission tomography/computed tomography (PET/CT) was performed to access the activity and extent of disease.