Imaging features and differential diagnosis of benign osseous cystic lesions: Aneurysmal bone cyst versus femoral neck herniation pit
DOI:
https://doi.org/10.12669/pjms.42.7.15878Keywords:
imaging features, diagnosis, aneurysmal bone cyst, femoral neck, herniation pit, X-ray, computed tomographyAbstract
Objectives: To investigate the imaging characteristics and differential diagnosis of aneurysmal bone cyst (ABC) and femoral neck herniation pit (HP).
Methodology: A retrospective analysis was performed of X-Ray and computed tomography (CT) imaging data from 28 patients with pathologically confirmed ABC and 31 patients with pathologically confirmed femoral neck HP, treated in Huzhou Shushan Geriatric Hospital between May 2022 and September 2025. The imaging characteristics of the patients were analyzed, and the efficacy of X-Ray and CT in distinguishing ABC from femoral neck HP was compared. The diagnostic efficacy of X-Ray and CT was assessed by Receiver Operating Characteristic (ROC) curves and the Area Under the ROC curve (AUC).
Results: X-Ray was able to identify 24 ABC cases of cystic expansile bone destruction, two cases of pathological fractures, and uneven bone septa. Twenty-nine femoral neck HP cases presented as round/slightly round lucent areas with sclerotic margins in the femoral neck. On CT, all 28 ABC cases exhibited osteolytic bone destruction characterized by varying degrees of expansile changes and a broader spatial distribution within the femoral neck compared to HP. Of them, 26 had bone shells, and two had fluid-fluid levels. On CT scans, femoral neck HP lesions manifested as small, focal bone defects strictly confined to the anterolateral subcortical region of the femoral neck; these lesions exhibited homogeneous or fluid-like soft-tissue density, thin sclerotic margins, and a characteristic relationship with the cortex where focal slit-like defects were occasionally visible. X-Ray had an AUC of 0.778 (95%CI: 0.670~0.886), while CT had a higher AUC of 0.912 (95%CI: 0.839~0.986).
Conclusion: There are distinct differences in X-Ray and CT imaging features between ABC and femoral neck HP. CT examination is more effective for the differential diagnosis of these two lesions.
