[Erdheim-Chester disease: radiological findings]. / Maladie d'Erdheim-Chester: apport de l'imagerie.

ABSTRACT

CONTEXT Erdheim-Chester disease is a rare non-Langerhans form of histiocytosis. For the past years, the disease has been reported with an increasing frequency, linked to a better knowledge of it's radiological pattern. Indead, it shows specific imaging appearances, that should be recognized. METHODS: We report four cases illustrating those typical imaging findings. RESULTS: Common X-rays films show bilateral and symmetric heterogeneous osteosclerosis of the metaphysis and the diaphysis in the lower limbs long bones, with paget's disease-like pattern. Magnetic resonance imaging depicts a replacement of the normal fatty bone marrow by a heterogeneous high intensity signal infiltrate on T1 fat-suppressed weighted imaging with intravenous injection of gadolinium and T2 fat-suppressed weighted sequences, sparing the subchondral bone. Bone scintigraphy reveals a pathognomonic bilateral and symmetric increased uptake affecting both diaphysis and metaphysis of the femur and the tibiae. Tomodensitometry enable to disclose visceral and vascular involvement, showing typical "hairy kidney" appearance and perivascular infiltration. CONCLUSION: Erdheim-Chester disease may be a life-threatening disease. A good knowledge of it specific imaging features seems to be crucial for early management and improved prognosis.