White adipose tissue uptake on F FDG PET/CT: A case report.

Three distinct types of adipose tissue have been characterized: brown, white, and beige. Brown adipose tissue (BAT) is typically found in specific regions including the anterior cervical, supraclavicular, axillary, and paravertebral areas. White adipose tissue (WAT) predominantly resides in subcutaneous layers, intramuscular spaces and among visceral organs, while beige adipose tissue is a subtype of WAT and is found interspersed within WAT deposits. BAT displays metabolic activity detectable on PET/CT scans, in contrast to WAT, which typically exhibits minimal to no uptake. Beige adipose tissue has been observed metabolically active in mice under certain conditions. Alterations in adipose tissue biodistribution are uncommon and have been linked to high-dose corticosteroid use. We present a rare case illustrating abnormal FDG uptake in WAT associated with high-dose corticosteroid therapy.