An unusual breast lesion: the ultrasonographic, mammographic, MRI and nuclear medicine findings of mammary hibernoma

Abstract

We report the case of a 42-year-old woman being treated for an ovarian cancer who was diagnosed at the age of 40. A CT-positron emission tomography (PET) scan performed as follow-up documented abnormal uptake in the right breast. Mammograms were negative for malignancy, while a focal hyperechoic lesion was observed on ultrasonography in the same breast. Thus, she was referred to our institution for breast MRI, which showed a focal area of enhancement with atypical features. Percutaneous biopsy was performed, and a mammary hibernoma was diagnosed. Radiological and pathological correlation was provided. To our knowledge, this is the only report that describes the features of this rare tumour on four different imaging modalities (mammography, ultrasonography, MRI and CT-PET).

Mammary Hibernoma: A Rare Entity

“…However, they may also present as an incidental finding on screening mammography or other radiologic imaging or rarely cause symptoms due to compression of adjacent structures. [4][5][6][7] RADIOLOGIC FEATURES Hibernomas arising in extramammary sites are usually radiolucent in contrast to the adjacent muscle; however, in fatty breast tissue, this mass is relatively radiodense. Mammary hibernoma appears as a well-defined, uniformly echogenic mass on breast ultrasonography and the radiologic differential includes other fatty lesions such as lipoma, interlobular stromal fibrous tissue, fibrolipoma, fibroadenolipoma, and early fat necrosis.…”

“…The CT-PET findings of mammary hibernoma are indistinguishable from malignancy, often leading to a false-positive radiologic interpretation and requiring a biopsy to exclude a malignant etiology. 4,6,7 PATHOLOGIC FEATURES The size of reported hibernomas ranges from 1 cm up to 24 cm, with 9 cm as average. 2 Grossly, this tumor is a lobulated, well-circumscribed, partially encapsulated mass and typically is yellowish brown with a rubbery texture.…”

Abnormal Mammary Adipose Tissue Environment of Brca1 Mutant Mice Show a Persistent Deposition of Highly Vascularized Multilocular Adipocytes

“…In particular, analysis of ductal structures from human neonates have demonstrated that these structure are often embedded within a connective tissue stroma and also in close proximity with nearby islands of multilocular, vascularized embryonic fat [43,44]. Additionally, there are several reports that have documented the observation of brown fat (hibernomas) in breast tumors [45-51]. Whether BRCA1 mutation carriers possess more BAT compared to non-BRCA1 mutations carriers remains to be determined.…”

Weichgewebstumor in der Nähe von Gelenken: Hibernom

“…Das MRT-Signal ist heterogen, da der Tumor einen variablen Anteil fibröser Septen besitzen kann. Ebenso ist die Gefäß-ausstattung des Tumors sehr variabel, jedoch ausgeprägter als in Lipomen [10]. Oftmals ist die Entdeckung ein Zufallsbefund.…”