Journal of Surgical Oncology 9 :563-566 ( 1 9 7 7 )

Hibernoma: Report of Two Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......................................................................................

RICHARD J. LUNG, M.D., STEPHEN LAPIDUS, M.D., STEPHEN H. MILLER, M . D . , a n d WILLIAM P. GRAHAM, 111, M.D.

Hibernornas are rare tumors of fat which are most often benign. Artcriographic findings may be mis- Icading with respect to the diagnosis of malignancy preoperatively. These uncommon tumors may be confused prior to surgery with lipomas, soft tissue sarcomas, and hemangiornas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......................................................................................... Key words: hibernoma

The ‘brown fat tumor’ of hibernoma is an uncommon, benign tumor of fat which has a favorable prognosis. These tumors were first described in human beings by Hatai arid Bonnot in the early 1900s (Angervall e t at., 1964). Shattock in 1908 proposed t h a t such fat masses in the cervical region of Cretins were enlargements of vestigal hibernating glands. Histologically these masses were similar and occupied a n analogous position to the hibernating glands found in the hedge hog (Sutherland et al., 1952). The blown fat commonly seen in hibernating glands led Gery in 1914 to suggest these tumors be named hibernuma (Gross and Wood, 1953).

Poroshin, 1962). Recently we have had the opportunity t o treat 2 patients with hiber- nomas, one of which was thought t o be a malignant tumor preoperatively.

The English literature reports a single case of a malignant hibernoma (Apatenko and

CASE REPORTS

Case 1

A 29-year-old inale developed a right anterior lateral chest wall mass 4 years prior to being seen at the Milton S. Hershey Medical Center. The mass was nontender, smooth, soft, and mobile and measured 15 X 11 cm. It was located in the right lateral chest wall midway between the anterior and posterior axillary lines at the level of the

From The Division of Plastic and Reconstructive Surgrry, the Milton S. Hershey Medical Center of The Pennsylvania State University, Hershey, Pennsylvania

Dr. Lapidus was the recipient of an American Cancer Society Fellowship, 1973-1974. His current address is 254 Church Street, Poughkeepsie, N. Y. 12061. Address reprint requests to him there.

563 @ 1977 Alan R . Liss, Inc., 150 Fifth Avenue, New York, NY 10011

564 Lung et al.

Fig. 1. Arteriogram of the avillary mass illustrating several vessels entering the tumor

fourth intercostal space. There were n o local inflammatory changes, and no bruit was heard over the mass. Routine laboratory studies and chest roentgenograms were within normal limits. A biopsy of the mass was attempted, but abandoned because of excessive bleeding .

In the light of this excessive vascularity, the possibility was proposed that this was a hemangioma and selective arteriography perfomled. This procedure revealed a tumor mass supplied by the subscapular artery with evidence of neovasculature and puddling of the contrast material within abnomial appearing vessels (Fig. 1). Roentgenogram of the mass was suggestive of a liposarcoma. Following completion of these studies, the inass was completely excised from heneath the serratus anterior muscle. It was 748 g in weight and consisted of a brown-yellowish fatty material (Fig. 3). Histologically, the tumor mass consisted of primitive fat cells in a highly vascularized stroma (Fig. 3 ) .

Hibernoma 565

Fig. 2. Cross section of the gross specimen removed.

Fig. 3. Histological sections of the tumor demonstratlng the vascularity of the fat cells. (X 600 hematoxylin and eosin stain.) Inset demonstrates vacuolization of fat cells. ( X 600-osmic acid stain.)

566 Lung et al .

Case 2

tumor of the left posterior thigh. The mass had been present for several years and was asymptomatic until 1 year prior to admission. At that time the tumor became uncom- fortable because of its location especially when the patient assumed a sitting position. Ex- amination disclosed a 6 X 6 cm lobular, nontender,knobby mass in the posterior aspect of the left thigh. The mass moved when the patient tightened her thigh muscles and suggested an inter- or intramuscular location o f the tumor. Exploration of the thigh in the operating room was performed and a 100 g yellow-brown fatty tumor was removed en bloc from within the semitendonous muscle. Histologically it was a mixture of univacuolated and multivacuolated fat cells in a vascularized stroma. In addition, multiple muscle bundle fibers were seen thus suggesting that this hibernoma was of the intramuscular variety (Fig. 2). The patient had an uneventful recovery.

A 33-year-old female was admitted to the Milton S. Hershey Medical Center for a

DlSCUSSlON

B I ~ W I I fat of the type found in hibernomas is often in the human embryo and fetus. Occasionally similar accumulations have been described in adults. The origin of this type of fat is obscure. These accumulations probably represent embryologic remnants o f tissue formed prior to the development of normal yellow-fat tissue (Sutherland et al., 1952).

ential diagnosis of soft tissue tuniors. The arteriographic findings of increased and irregular vascularity within a soft tissue tumor or fatty tumor implies the presence of a malig- nancy; however, malignant hibernonias with such findings are apparently very rare.

From a practical point of view, it IS important t o include hibernoma in the differ-

CONCLUSION

Hibernotnas are rare tumors of fat which are most often benign. Arteriographic findings may be misleading with respect t o the diagnosis of malignancy preoperatively. These uncommon tumors may be confused prior to surgery with liponias, soft tissue sarcomas, and hemangiomas.

ACKNOWLEDGMENTS

This work was supported by a grant from the Irvin Zubar Memorial Cancer Fund.

REFERENCES

Angervall, L., Nilsson. L., and Stcner, B. (1964). Microangiograptiic dnd histological studies in two

Apatenko, A. K . and Poroshin, K.K. (1962). O n morphology and histogenesis of hibernorna. Arkli.

(;ross, S. and Wood. C. (1953). Hibeinonia. Cancer 6:159. Sutherland, J.C., Callatian, W.P., and Campbcll, G.L. (1952). Hihernoma: A tumor of brown fat.

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