Aneurysmal bone cyst
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Presentation
One month history of Left hip pain with restricted movement
Patient Data



The MRI sequences demonstrate a multiloculated expansile cystic lesion of the left femoral head, centered on the posterior aspect of the epiphysis and upper femoral neck, composed of cystic cavities of low signal on T1WI, high signal on T2WI with fluid-fluid levels (blood products) and no enhancement seen on postcontrast sequences. A cortical breach is noted at the superolateral aspect of the lesion with reactive joint effusion, synovial enhancement as well as bone marrow edema. No underlying bone lesion is seen. An amyotrophy of the ipsilateral gluteal muscles is noted.
Case Discussion
MRI features highly suggestive of an aneurysmal bone cyst (ABC)
On MRI the main differential diagnosis includes:
- lesions with intrinsic fluid-fluid levels
- lesions from which an ABC may arise: