Jung-Won Ha, M.D.,#Hak-Sun Kim, M.D.,Jin-Oh Park, M.D.,Jun-Young Chung, M.D.,Ju-Yeon Pyo, M.D.,$
and Eun-Su Moon, M.D.
Department of Orthopedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
#Department of Orthopaedic Surgery, National Health Insurance Corporation Ilsan Hospital, Seoul, Korea.
$Department of Diagnostic Pathology, Yonsei University College of Medicine, Seoul, Korea.
Address reprint requests to: Eun-Su Moon, M.D. Department of Orthopaedic Surgery, Yong-Dong Severance Hospital, Yonsei University College of Medicine, Dogok-Dong, Kangnam-Ku, Seoul, Korea, 135-720. Tel: 82-2-2109-3418, Fax: 82-2-573-5393, Email: mes1007@yumc.yonsei.ac.kr
Abstract
Hibernoma is a rare benign tumor of a brown fat origin with hypervascularity. Although the magnetic resonance imaging features resemble a liposarcoma, its malignant potential is unknown. A complete local excision with meticulous hemostasis is the treatment of choice. We present a case of hibernoma in the psoas muscle with a review of the relevant literature.
Keywords: Psoas muscle; Hibernoma; Benign tumor
Figures
Fig. 1 On computed tomography, about 4 × 4 cm sized, lobuated and multiseptated fatty mass was noted in right psoas muscle area extending over T12 to L2 vertebra. The mass showed an increased attenuation compared with subcutaneous fat, and decreased attenuation compared with muscle.
Fig. 2 On preoperative MR imaging, a well marginated and lobulated mass was found on posterior aspect of right kidney being contiguous to right psoas muscle. (A) On T1 weighted imaging, the signal intensity of the mass was intermediate between those of skeletal muscle and subcutaneous fat. (B) On T2 weighted imaging, the mass was heterogenous with somewhat increased signal intensity.
Fig. 3 On PET scan, there was significantly increased FDG uptake on the mass. However there was no increased uptake in other parts of the body indicating metastasis.
Fig. 4 Preoperative angiography showed a hypervascular mass being fed from branch vessels of 1-2, 2-3, 3-4 lumbar artery. Preoperative embolization was performed for the prevention of intraoperative massive bleeing and extracompartmental contamination in case of malignancy.
Fig. 5 On gross examination, the mass was about 7 × 4.5 × 4 cm sized and encapsulated with rubbery hard consistency. On serical sections, the cut surface showed multi-lobulation with intervening streaks.
Fig. 6 Histologically, the mass showed a mixture of brown and white adipose cells and was divided into lobules by well vascularized connective tissue. The brown adipose cells are characterized by polygonal, multivacuolated cells with abundant , granular cytoplasm and small, central nucleus.(H-E stain, x100)
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Furlong MA, Fanburg-Smith JC, Miettinen M. The Morphologic Spectrum of Hibernoma: A Clinicopathologic Study of 170 Cases. The American Journal of Surgical Pathology 2001;25:809–814.
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