Introduction: We report on a rare case of an atypical located aneurysmal bone cyst (ABC) in the patella presenting with pathological fracture after trauma.
Materials and methods: Using all available diagnostic modalities and by means of ultrasound-guided core-needle biopsy an unclear and suspected pathological fractured cystic bone lesion in the patella of a young man could be further clarified.
Results: The acquired images suggested the diagnosis of a pathological fractured aneurysmal bone cyst after mild trauma. However, due to the extraordinary location and clinical presentation the diagnosis was secured by means of ultrasound-guided biopsy through a small cortical gap.
Conclusion: As shown in this rare case of an atypical aneurysmal bone cyst of the patella, the quite seldom but sometimes possible ultrasound-guided biopsy of intraosseous lesions can help to achieve the diagnostic clarification and should also be taken into account as a non-standard procedure.
Keywords: Aneurysmal bone cyst; Patella; Pathological fracture; Ultrasound; Ultrasound-guided biopsy.