Aneurysmal Bone Cyst-Medial Cueniform-MRI

Evidence of an expansile lesion involving the medial cueinifom bone with areas of marrow signal alteration showing isointense signal on T1 WI and hyperintense on T2 and STIR images along with areas of blood fluid levels. There is associated surrounding myofascial edema. Neurovascular bundles are preserved. These finings likely indicate an aneurysmal bone cyst (possible sequale to previous injury)

Learning Points

 The etiology is unknown, although it is now commonly accepted that benign bone cysts are caused by trauma.

 These tumors are benign and are characterized by expansile compartmentalization within cancellous bone.

 The lesions consist of blood filled spaces filled with connective tissue septa containing bone or osteoid and osteoclastic giant cells.

 The cyst is increasingly painful as it begins to expand, and diagnosis will usually be confirmed by ‘fluid-fluid’ levels and compartmentalization seen on CT and MRI.