Hibernoma: A clinical model for exploring the role of brown adipose tissue in the regulation of body weight?

Abstract

Context: Hibernoma is a rare benign tumor histologically similar to brown adipose tissue. Some studies reported weight loss in patients with this tumor; however, the mechanisms have never been investigated. Objective: The purpose of this study is to explore the impact of hibernoma resection on the wholebody metabolism. Patient and Methods: A68-year-old woman was examined after a weight loss of 10 kg in 6 months. Body composition, food intake, physical activity, blood levels of thyroid hormones, and lipid profile were assessed before surgery and during 1 year after surgery. The patient's resting energy expenditure (REE) over time was compared to a control group of 18 matched healthy volunteers. Results: Within 1 year after hibernoma resection, the patient gained 15 kg of body weight. This was associated with fat mass gain (+41%), mainly in the abdominal region (+48%). The patient also developed hepatic nonalcoholic steatosis, mild hypertriglyceridemia, and reduced levels of highdensity lipoproteins. REE increased during the dynamic phase of weight gain, compared to the presurgery measurement, and returned to baseline after 1 year. Food intake was increased by 37.5% 6 weeks after resection of the hibernoma and returned to baseline values within 6 months. Conclusions: In our study conditions, hibernoma did not alter REE, but weight gain did. Specific physical activities and dietetic follow-ups are suggested for those patients to prevent excess fat mass gain and metabolic disorders after hibernoma resection. More studies should focus on hibernoma mechanisms inducing weight loss. (J Clin Endocrinol Metab 99: 1-6, 2014). © Copyright 2014 by The Endocrine Society.