Hibernoma: Intense Uptake on F18-FDG PET/CT

Abstract

Hibernoma is a rare benign but metabolically active tumor of brown fat origin, that can have cross-sectional imaging characteristics similar to those of other fat-containing tumors, such as lipomas and liposarcomas, and its presence can lead to false-positive interpretation by exhibiting increased F18-fluorodeoxyglucose (F18-FDG) activity. A 46-year-old woman was diagnosed with dermatofibrosarcoma protuberans underwent F18-FDG positron emission tomography/computed tomography (PET/CT) for detecting recurrence after excision. F18-FDG PET/CT showed incidental intense uptake in the back in addition to increased F18-FDG uptake at the previous lesion site. To our knowledge, this is the first case report of intense F18-FDG uptake in hibernoma in Korea.

Keywords: Dermatofibrosarcoma protuberance; Hibernoma; PET/CT.

Fig. 1

Transaxial F18-FDG PET/CT images show a recurrent dermatofibrosarcoma protuberans in the left retromastoid area with SUVmax of 2.75

Fig. 2

Transaxial (a, b), sagittal (c, d) and coronal (e, f) F18-FDG PET/CT images show a 2 × 4 × 4.5-cm sized hypermetabolic mass in the subcutaneous layer of the left back at T9-T10 level with SUVmax of 12.83 in 1 h

Fig. 3

Contrast-enhanced MRI images show the left back mass in subcutaneous layer at T9-T10 level with heterogenous T1 and T2 hyperintensity (hypointense to adjacent subcutaneous fat) (a, b) and intense enhancement with a linear hyperintensity entering the mass (c, d). The mass is not suppressed on fat-saturation image (e)

Fig. 4

Microscopic view of the tumor shows round or polygonal multivacuolated cells and mature adipose cells, and many small vessels