Hibernomas: clinicopathological features, diagnosis, and treatment of 17 cases

Hibernomas are rare benign adipose tumors composed of brown fat cells with granular, multivacuolated cytoplasm admixed with white adipose tissue. They account for 1.6% of benign lipomatous tumors and approximately 1.1% of all adipocytic tumors. They are more common in the third and fourth decades of life. The most common location is the thigh, followed by the shoulder, back, and head and neck. Four histological types have been reported; abundant vascularity is characteristic, and atypias are rare. The treatment of choice for hibernomas is complete surgical excision. Metastases or malignant transformation have not been reported.This article presents a series of 17 patients with hibernomas diagnosed and treated at our institution from January 1986 to December 2009. Six men and 11 women (M:F, 1:2) had a mean age of 38 years (range, 10 months to 64 years). All patients underwent surgical treatment; 14 patients had marginal and 3 had wide excision. Adjuvants such as radiation therapy, chemotherapy, or embolization were not administered for any patient. The most common symptom was a painless palpable mass, followed by a tender or painful mass; in 2 patients, the tumor was an incidental finding. The duration of symptoms ranged from 1 month to 10 years (mean, 27 months). The most common location was the thigh, followed by the buttock, scapula, and neck. The most common histological variant was the typical variant followed by the lipoma-like variant. At a mean follow-up of 5 years (range, 1-9 years), local recurrences were not observed.