Aneurysmal bone cyst of the distal humerus

Case contributed by Domenico Nicoletti


Swollen elbow with little pain and slow growth. The swelling is hard and immobile.

Patient Data

Age: 8 years
Gender: Male

Humerus distal metaphysis osteolytic lesion with expanded cortex that does not appear interrupted.

There are multiple fluid-fluid levels within the cystic spaces. MRI is useful to confirm the multiple fluid-fluid levels and the non-homogeneity of the lesion. ABC appears on both T1 and T2 MRI with a low signal rim encircling the cystic lesion.

Case Discussion

Aneurysmal bone cysts (ABCs) are a bone hamartoma (malformation) that consists of reactive hemorrhagic tissue that grows inside of a bone. The development and growth of an aneurysmal bone cyst is variable and can be extremely slow, even years, or very fast in the most aggressive forms that even reach large sizes. The metaphysis of long bones and vertebrae are the most common site but they can occur in any bone.

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