Presentation
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
From the case:
Fallen fragment sign of unicameral bone cyst
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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.
From the case:
Fallen fragment sign of unicameral bone cyst
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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.