A case of Erdheim-Chester disease initially mistaken for Ormond's disease.

BACKGROUND

A 54-year-old man presented with fever, abdominal pain, anemia, elevated C-reactive protein level and decreased renal function. Idiopathic retroperitoneal fibrosis (Ormond's disease) had been diagnosed in the past, leading to surgical ureterolysis. Re-evaluation of the CT scans and histological biopsy samples revealed unusual sclerosis of the long bones and diffuse infiltrates of foamy histiocytes in the bone marrow and the retroperitoneum.

INVESTIGATIONS: Physical examination, laboratory tests including hemoglobin concentration, erythrocyte sedimentation rate, C-reactive protein level, beta2-microglobulin level, creatinine level, CT of the chest and abdomen, bone scintigraphy, bone marrow and soft tissue biopsies and immunohistochemistry.

DIAGNOSIS: Erdheim-Chester disease with retroperitoneal fibrosis and bone sclerosis.

MANAGEMENT: Treatment with glucocorticoids failed. The patient's symptoms improved significantly after initiation of interferon-alpha therapy.