Fallen fragment sign of unicameral bone cyst

Case contributed by Dr Aneta Kecler-Pietrzyk


6 year old girl post fall. She injured her left humerus 2 days ago, and has ongoing shoulder/proximal humerus pain since. Restricted motion of the shoulder joint. No neurovascular deficit.

Patient Data

Age: 6 years
Gender: Female

Slightly expansile, lucent lesion in the proximal humeral diaphysis with lateral cortical break in keeping with an acute pathological fracture. A fallen bone fragment is seen within the lesion. 

Annotated fallen fragment sign (arrow).

Case Discussion

The fallen fragment sign is virtually pathognomonic for a unicameral simple bone cyst, however, there are a few case reports in the literature that report this sign in other cystic bone lesions e.g. eosinophilic granuloma 1.  

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Case information

rID: 55115
Published: 21st Aug 2017
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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