Hibernoma of the antero-l
Fatty tumour;Brown fat
a is sl. W
the diagnostic and therapeutic elements of this type of tumour, whose differentialdiagnosis of liposarcoma.
H d benigti scribedLe ave beliterature.1,2 It is a tumour developed from foetal
Diagnosis is difficult and there is often confusion
mass that had been enlarging for 2 years on the
Recent ultrasonography showed an increase in
An associated Doppler examination revealed
showed a hypodense, rather vascular mass, with
British Journal of Plastic Surgery (2005) 58, 859861
* Corresponding author. Address: Service de chirurgie plastiquedoi:10.1016/j.bjps.2005.01.020rich vascularisation of this structure. CT scanwith a liposarcoma or intramuscular lipoma. Treat-ment is surgical since only excision can provide adiagnosis and eliminate differential diagnoses. Wepresent a case of hibernoma of the lateral thigh.
the diameter of the right thigh with a fibrousstructure, hyperechoic and well delineated,measuring 2 cm in thickness, over 12 cm in heightand over 10 cm in width, corresponding to anintramuscular lesion of the anterior side of thethigh.brown fat tissue, vestigial remnants of the evol-ution of the species.2 In adults, it is usually found inthe regions where islets of brown fat remain in thescapular3 and posterior cervical regions and morerarely, in the folds of the buttocks or the thigh.46
external side of the right thigh. She presented nochronic pathology and had no surgical history.
The clinical examination revealed a well definedsolid tumour, adherent to surrounding muscle butwhich caused no pain on palpation.ibernoma is a rare anssue that was first dess than 200 cases hrights reserved.
n tumour of the softby Merckel in 1906.en reported in the
A 28-year-old woman presented with a voluminousq 2005 The British Association of Plastic Surgeons. Published by Elsevier Ltd. AllC. Della Volpe, B. Salazard*, D. CasaJ.F. Bartoli, G. Magalon
Department of Plastic and Reconstructive Surgery, HMarseille Cedex 05, France
Received 25 May 2004; accepted 14 January 2005
Summary Hibernompresents as a voluminoufat can remain in adultsateral thigh
ova, H. Vacheret,
ital de la Conception, 147 Boulevard Baille, 13385
s a rare benign tumour of brown fat. In most cases itow-growing mass in the regions where remnants of browne report a case of a hibernoma on the thigh and presentoccupied the rectus femoralis muscle and its
S0007-1226/$ - see front matter q 2005 The British Association of Plastic Surgeons. Published by Elsevier Ltd. All rights reserved.
conception, 13005 Marseille, France. Tel.:C33 610 310 380.E-mail address: email@example.com (B. Salazard).central necrosis (Fig. 1). The lesion essentiallyet reparatrice du Professeur Guy Magalon, Hopital de la
inferior two-thirds encompassed and was attachedto the entire vastus lateralis. The latter wascompressed, but the tumour appeared had clearlydefined margins. There was no identifiable associ-ated bone lesion. The chest X-ray was normal. Nodiagnosis was made at that time.
MR imaging demonstrated on T1W a superficialmass on the antero-lateral side of the thigh onmixed spontaneoushyperenhancement (Figs. 2 and3).It showed infiltration with compression on theforward part of the rectus femoralis, flatteningwith its posterior part of the vastus lateralis muscleand the femoral pedicle by pushing them againstthe femoral bone. T2W made it possible to deletethe fatty structure of the lesion in order to observesome blood flow phenomena such as suffusion.Injection of gadolinium clearly enhanced the lesion.MR imaging concluded this was a lesion in the softtissue with a fatty matrix because of the relativelywell-defined, but mixed T1-weighted signal. Thepossible diagnosis of liposarcoma dictated surgicalexcision.
Surgical excision was performed under generalanaesthesia. A deep-seated tumour was foundcompressing the muscles in their compartment.Dissection began with the distal part where it wasnot adherent, then proximal where the tumour wasattached to the deep muscles and the crural
Figure 1 CT scan of the thigh.
C. Della Volpe et al.860Figure 2 MR imaging, T1-weighted image, sagittalview.pedicle. The surgical specimen was sent to thehistology laboratory. Biopsy samples were alsotaken near the lesion.
The histological results reported a proliferationwith lobular architecture (Fig. 4) composed ofround or oval monomorphic micro-vacuolatedcells that contained eosinophilic granules (Fig. 5),with no mitotic cells or nuclear atypia, character-istic of a brown fat benign tumour or hibernoma. Notumoural infiltrate was detected in biopsies fromsurrounding tissues.
Figure 3 MR imaging, T1-weighted image, axial view.
2. Chen DY, Wang CM, Chan HL. Hibernoma: case report andliterature review. Dermatol Surg 1998;24(3):3935.
1994;23(2):1379.7. Deseran MW, Seeger LL, Doberneck SA, Ecckardt JJ. Hiber-
Hibernoma of the antero-lateral thigh 861Discussion
Brown fat is a remnant from the evolution ofspeciesit participates in the thermogenesis ofhibernating mammals. In man, it is found physio-logically in newborns in the axillary and thesubpleural regions but is said to disappear after 8weeks of life.3
Slight quantities can remain in adults in thescapular region and more rarely, in the axillary,3
mediastinal, cervical, gluteus regions, the thigh,46
or the popliteal cavity which are the favouredregions for hibernomas.7 No malignant transform-ations have ever been reported in the 100 or socases in the literature.
Today, it is generally agreed that this benigntumour can be diagnosed by MRI with the followingcharacteristics: T1- and T2-weighted images, evo-cative of a fatty signal. In T1, the signal of theentire tumour was not exactly similar but wasdiscretely lower than that of the subcutaneous fat.This signal was evocative of a hibernoma.8,9 In T1inside the tumour, there were areas of intermedi-ate signals between that of the muscle and thesubcutaneous fat. Contrast enhancement was sig-nificant after injection of gadolinium, particularly
Figure 4 Histologic image with lobular proliferation.in low-signal areas. In T2, the mass signal was oftenvery near that of the subcutaneous fat.8,9
Surgical excision is indispensable because of thediscomfort that is often associated with the tumourand more especially, for histologic confirmation.3. Kunin N, Henno S, Verhoye J-P, Moreau L, Mambrini A.Hibernome de la region axillaire. J Chir 1997;134(3):11921.
4. Mugel T, Ghossain MA, Guinet C, Buy J, Bethoux J, Texier P,et al. MR and CT findings in a case of hibernoma of the thighextending into the pelvis. Eur Radiol 1998;8(3):4768.
5. Lewandowski PJ, Weiner SD. Hibernoma of the medial thigh.Clin Orthop 1996;330:198201.
6. Seynaeve P, Montelmans L, Kockx M, Van Hoye M, Mathijs R.Case report 813: hibernoma of the left thigh. Skeletal RadiolIndeed, hibernoma resembles liposarcoma diagnos-tically at a local stage. The rate of development andthe metastatic potential of these lateral tumoursrequire rapid surgical treatment confusion betweenhibernoma and liposarcoma is increased since bothshow onset in the third or fourth decade with apredominance in women (58% of the cases).8,9
1. Furlong MA, Fanburg-Smith JC, Miettinen M. The morphologicspectrum of hibernoma: a clinicopathologic study of 170cases. Am J Surg Pathol 2001;25(6):80914.
Figure 5 Histologic image with micro-vacuolated cellsthat contained eosinophilic granules.noma of the right gracilis muscles. Skeletal Radiol 1994;23(4):3012.
8. Atilla S, Eilenberg SS, Brown JJ. Hibernoma: MRI apparance ofrare tumor. Magn Reson Imaging 1995;13(2):3357.
9. Alvine G, Rosenthal H, Murphey M, Huntrakoon M. Hibernoma.Skeletal Radiol 1996;25(5):4936.
e antero-lateral thighCase reportDiscussionReferences