Aneurysmal bone cyst (ABC)

Case contributed by Ammar Haouimi
Diagnosis probable


Painful swelling of the distal tibia. No history of trauma.

Patient Data

Age: 14 years
Gender: Female

Large multiloculated expansile cystic lesion eccentrically located in the posterior aspect of the distal tibial metaphysis extending to the epiphysis with thin-walled cavities containing fluid-fluid levels and enhanced internal septations. No evidence of soft tissue extension. The bone window shows a cortical breach.

Case Discussion

CT features of an eccentric multiloculated expansile lesion of the tibial metaphysis with fluid-fluid levels most consistent with an aneurysmal bone cyst (ABC).

It is important to remember that the presence of fluid-fluid levels, although characteristic of aneurysmal bone cysts, is by no means pathognomonic, and is seen in other lesions as well, both benign and malignant (e.g. giant cell tumors (GCT), chondroblastoma, simple bone cysts and telangiectatic osteosarcomas).

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