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Musculoskeletal Imaging

E2531. Incidentalomas of the Proximal Femur: When to Be Worried?

Bai J,  Huang M,  Comito M,  Kolanko N. Stony Brook University Hospital , Stony Brook, NY

Address correspondence to J. Bai (james.bai@stonybrookmedicine.edu)

Background Information: Proximal femur incidentalomas can pose a diagnostic dilemma in daily clinical practice, whether when interpreting dedicated hip or pelvic radiographs, or when seen on a CT scan of the abdomen and pelvis. Proper imaging characterization plays an important role in guiding the clinician during management of these patients. Recognizing features of benign lesions can save patients from unnecessary invasive procedures, such as biopsy.

Educational Goals/Teaching Points: Through a series of cases of benign and malignant lesions, this exhibit aims to familiarize the radiologist with the hallmark characteristics of benignity, and highlight more worrisome features of aggressive lesions that warrant further workup. Additionally, the exhibit will share our experiences at managing some of the more equivocal cases.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: Case-based review of both benign and malignant incidental proximal femur lesions consists of image review across multiple modalities, including radiography, CT, MRI, and bone scintigraphy, and includes surgical specimen with pathologic correlation, when available. Fibrous dysplasia is one of the most common lesions of the proximal femur. This exhibit demonstrates typical cases (ground-glass matrix lesion in the medullary cavity), as well atypical imaging appearances of fibrous dysplasia (fibrous dysplasia with cartilaginous metaplasia and cystic fibrous dysplasia). Other common benign entities frequently encountered in the proximal femur include fat-containing lesions, such as intraosseous lipoma and liposclerosing myxofibrous tumor. This exhibit demonstrates typical imaging findings of these entities on radiography, CT, and MRI. Finally, chondroid lesions and intraosseous cysts of the proximal femur are demonstrated through radiography, CT, and MRI, with a discussion of the hallmark characteristic features of each entity. Primary bone malignancy and metastatic lesions can both be encountered in the proximal femur. To this end, cases of chondrosarcoma, multiple myeloma and metastatic lesions from prostate, breast, and lung cancer are covered in this review.

Conclusion: The exhibit provides case-based review to demonstrate benign and worrisome features of proximal femur incidentalomas that will help guide the clinicians during management of these patients.