Femoral hibernoma: unique intraosseous tumor

A 51-year-old woman was admitted to the emergency department after a fall down the stairs. After physical examination, radiographic images were taken to rule out fractures. Noncontrast computed tomography revealed a well-circumscribed, mildly sclerotic lesion at the level of the trochanter major on the lateral aspect of the right thigh (Fig. 1a, arrow). In the patient, who did not have any clinical symptoms at the lesion level, further examination of the lesion was planned under elective conditions. Magnetic resonance imaging revealed a subcortically located lesion at the level of the right greater trochanter, an intermediate signal on T1-weighted images (Fig. 1b, arrow) and showing peripheral contrast enhancement in a post-contrast series (Fig. 1c, arrow). Due to the abnormal radiological nonspecific appearance of the lesion, bone scintigraphy was performed to evaluate whether the lesion was solitary and physiologically active. The bone scan images showed increased Tc-99m methylene diphosphonate activity at the same location in the femur (Fig. 1d, arrow). Additionally, bone scintigraphy showed bilateral involvement in the mandible (Fig. 1d, arrowheads). At our radiology clinic a biopsy was suggested, stating that the lesion had many differential diagnoses such as metastasis and lymphoma. A CT-guided biopsy identified the lesion as an intraosseous hibernoma (Fig. 2).

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