Massive Abdominal Wall Hibernoma: Case Report and Literature Review of a Rare Soft-Tissue Tumor

Abstract

Hibernoma is a rare benign tumor arising from remnants of fetal brown adipose tissue. This tumor was first described by Merkel in 1906. The brown fat is a specialized form of fat found in the hibernating and nonhibernating animals such as rats, cats, monkeys, rabbits, and humans. A 27-year-old man presented with a painless, enlarging, anterior abdominal wall mass, which, upon core-needle biopsy, was found to be hibernoma. This was evaluated with abdominal computed tomography, which showed a heterogeneous mass that contained fat. At operation, the entire mass measuring 30x25x6 cm lying below the external oblique muscle was excised with a cuff of normal tissue. Hibernoma is a rare, slow-growing benign soft tissue tumor composed of brown fat that is successfully treated by complete excision while preserving all related vital structures. Unlike lipoma, hibernoma is well vascularized and therefore good hemostasis must be achieved at surgery to prevent postoperative bleeding or hematoma. No case of recurrence has been previously reported.