Sonographic findings of hibernoma. A report of two cases.

We present 2 cases of hibernoma, a rare lipomatous tumor arising from brown fat tissue. In each case, a hyperechoic mass in comparison to surrounding musculature combined with elevated vascularization was highly suggestive of a liposarcoma. As a rule, malignancy cannot be excluded safely by imaging modalities, and a preoperative biopsy should be performed. Although rare, hibernomas should be considered in the differential diagnosis of lipomatous soft-tissue tumors.