Epiphyseal aneurysmal bone cyst

Case contributed by Angel Romero Domínguez
Diagnosis certain

Presentation

Chronic insidious left knee pain.

Patient Data

Age: 13 years
Gender: Male
x-ray

Well-defined, lytic lesion at the distal femoral epiphysis. The lesion is expansile, with cortical thinning, esclerotic edge, narrow transition zone, without periostal reaction or soft tissue involvement.

There is a multiloculated T1W heterogeneous hypointense cystic lesion demonstrating fluid-fluid levels centered in the physis. There is adjacent bone marrow edema and mild joint effusion.

 

Histopathological report

Biopsy report:

  • multiple variable sized cystic spaces filled with blood in different stages, separated by fibrous septa  
  • scattered osteoclast-like multinucleated giant cells
  • negative for malignancy

Case Discussion

MRI demonstrates the characteristic fluid-fluid levels of an aneurysmal bone cyst 1. The histopathological examination is confirmatory.

This location of the aneurysmal bone cyst is extremely rare, with few cases reported in the world literature 2-5.

 

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