MR imaging of brown tumour with fluid-fluid levels: a report of three cases

Fluid-fluid levels on CT and MR imaging are a typical feature of aneurysmal bone cysts but have also been reported in many other osseous lesions conta ining haemorrhage. We report fluid-fluid levels in four brown tumour in thr ee patients with primary hyperparathyroidism in which the initial radiologi cal diagnosis was thought to be a bone tumour. To the authors' knowledge, t his is the first time that association has been reported in the internation al literature.