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Indexed/Abstracted in: EMBASE, Scopus, Emerging Sources Citation Index
Online ISSN 1827-1782
Pompili G. 1, Scrimali L. 1, Galia A. 2, Scilletta A. 1, Tamburino S. 1, Siragò P. 1
1 Department of Plastic Surgery, University of Catania/Cannizzaro Hospital Catania, Italy
2 Department of Pathological Anatomy, Cannizzaro Hospital Catania, Italy
Hibernoma is uncommon benign lipomatous tumors which show differentiation toward brown fat, resembling the brown fat of hibernating animals. Is usually located peripherally, expecially in the thigh, but the overall anatomic distribution is very wide. Although most cases are subcutaneous, up to 10% are intramuscular, expecially in the extremities.Hibernoma affects only adults of either sex, with peak of incidence between 3rd or 4th decades, it is rare in children. Hibernoma shows slow-growing, invariable benign clinical course. Usually is asymptomatic, but can become large mass over time and compress and displace surrounding structures. Its radiologic appearance is commonly mistaken for malignant liposarcomas, so hibernoma can only be diagnosed histologically. Usually, hibernoma is a benign, subcutaneous or intramuscular, freely movable, non tender mass, ovoid in shape. Histological examination reveals a well-circumscribed, encapsulated, lobulated by thin septa and homogeneous tumor, reddish-brown in colour and with a rich vascular network. Despite tumor is encapsulated infiltration of adjacent structures, particularly striated muscle may be present. Microscopically is composed of multivacuolate adipocytes, resembling those seen in brown fat, mixed with variable proportions of univacuolate adipocytes, similar to those seen in typical lipomas and normal adult adipose. Four morphologic variants of hibernoma have been identified: typical, myxoid, spindle cell, and lipoma-like. In typical hibernoma there is no real differential diagnosis, but lipoma-like variant contains lipoblast-like cells, that can lead to a misdiagnosis of atypical lipoma/well differentiated. Appropriate treatment is complete excision of the hibernoma, with no potential of recurrence and metastasis after resection.