Case Report. MRI of a Hibernoma

Abstract

Hibernomas are benign tumors derived from brown fat that most often present as painless, slowly enlarging masses in the interscapular region. Because these lesions have a heterogeneous appearance and contain fat, they mimic liposarcomas on CT and MR, requiring biopsy for definitive diagnosis.

Sonographic findings of hibernoma. A report of two cases

“…The present 2 cases demonstrate that, in addition to malignant softtissue tumors, hibernoma is to be considered in the differential diagnosis in the case of increased vascularization. The presence of vascular channels on color Doppler sonography in a case of hibernoma has also been reported by Cook et al 1 Cross-sectional imaging studies (CT or MRI) are needed for preoperative planning. 2 The hypervascularization of the tumor explains the heterogeneous contrast enhancement seen on CT and MRI in most cases.…”

“…In contrast to lipomas, however the overlying skin can be warmer due to the rich vascularization of the tumor. 1 As a first diagnostic step for a palpable softtissue tumor, sonography is recommended. Grayscale images usually cannot distinguish reliably a lipoma, hibernoma, or low-grade liposarcoma.…”

“…2,4 Most authors recommend a preoperative open biopsy in lesions with a diameter of more than 3 cm or a wide resection of tumors less than 3 cm in diameter. 1,9 Accurate diagnosis can be facilitated by selective sampling of the area of increased vascularization, which most likely represents a site of viable malignancy. 6 However, because of the increased potential for hemorrhage, some authors have chosen not to perform a biopsy when a hibernoma is suspected.…”

“…It has the function of fat storage and is hypervascularized in contrast to white adipose tissue. 1,2 The amount of brown fat decreases during childhood, and in adults it accounts for only 1% of adipose tissue. We report the sonographic findings in 2 cases of this rare tumor of brown adipose tissue with its clinical, correlative imaging, and histopathological features.…”

Dumbbell-shaped thoracic hibernoma: computed tomography and magnetic resonance imaging findings

“…In addition, prominent branching and serpentine structures (low signal intensity with all MR pulse sequences) are often seen with contrast enhancement. [11][12][13][14][15] In our case, a dynamic-contrast MRI study showed branching and serpentine structures with early contrast enhancement. Although these features may initially suggest well-differentiated liposarcoma, this type of vascularity is not prominent in liposarcomas and may be an important feature for differentiation.…”