18F-2-fluoro-2-deoxyglucose uptake in white adipose tissue on pediatric oncologic positron emission tomography (PET)/computed tomography (CT)

White adipose tissue uptake on 18F 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.

FDG altered biodistribution in white adipose tissue, a rare entity: case report and review of the literature

PURPOSE

Altered 18F-fluorodeoxyglucose (FDG) biodistribution due to patient factors such as exercise and inadequate fasting are well established causes of limited diagnostic efficacy. In addition, medications such as G-CSF are known to affect uptake of FDG by bone marrow and spleen. In this study, we present a case of increased white adipose uptake in a pediatric lymphoma patient who recently received high dose dexamethasone and review the relevant literature regarding this rare and poorly understood pattern of altered FDG biodistribution.

METHODS

A 14-year-old male patient diagnosed with B-cell lymphoblastic lymphoma underwent FDG-PET/CT for restaging shortly after completing an induction chemotherapy regimen. Images revealed diffuse FDG uptake localizing to white adipose tissue, attributed to the 29-day course of dexamethasone which was completed two days prior. A diagnostically adequate study with relative normalization of FDG biodistribution was obtained seven days later.

RESULTS

In our review of the literature, diffuse FDG uptake by white fat is a rare occurrence and has only been reported by a few case reports and early observational studies. In addition to patients receiving corticosteroids, other cases of medication-induced adipose remodeling such as patients receiving highly active antiretroviral therapy have been documented with similar patterns of increased white adipose tissue activity.

CONCLUSION

Corticosteroid-induced white fat uptake of FDG is a rare phenomenon that can limit diagnostic accuracy of FDG-PET/CT and necessitate repeat imaging. Current evidence suggests that a wait period of at least one week after discontinuation of corticosteroids is sufficient to allow for decreased white fat uptake and increased diagnostic accuracy.

Diffuse White Adipose Tissue 18F-FDG Uptake-An Unusual Finding on 18F-FDG PET/CT

ABSTRACT

Brown adipose tissue of cervical, supraclavicular, and paravertebral regions can show increased FDG uptake. But human white adipose tissue (WAT) shows negligible FDG uptake on 18F-FDG PET/CT scan. We present a case of carcinoma cervix treated with concurrent chemoradiation. 18F-FDG PET/CT shows altered biodistribution of FDG with intense FDG uptake throughout the WAT. Later on, patient confirmed taking herbal medication for herpes zoster infection, which could contain corticosteroids, resulting in enhanced WAT uptake of 18F-FDG.

Amidation-Modified Apelin-13 Regulates PPARγ and Perilipin to Inhibit Adipogenic Differentiation and Promote Lipolysis

With the adjustment of human diet and lifestyle changes, the prevalence of obesity is increasing year by year. Obesity is closely related to the excessive accumulation of white adipose tissue (WAT), which can synthesize and secrete a variety of adipokines. Apelin is a biologically active peptide in the adipokines family. Past studies have shown that apelin plays an important regulatory role in the pathogenesis and pathophysiology of diseases such as the cardiovascular system, respiratory system, digestive system, nervous system, and endocrine system. Apelin is also closely related to diabetes and obesity. Therefore, we anticipate that apelin-13 has an effect on lipometabolism and intend to explore the effect of apelin-13 on lipometabolism at the cellular and animal levels. In in vitro experiments, amidation-modified apelin-13 can significantly reduce the lipid content; TG content; and the expression of PPARγ, perilipin mRNA, and protein in adipocytes. Animal experiments also show that amidation modification apelin-13 can improve the abnormal biochemical indicators of diet-induced obesity (DOI) rats and can reduce the average diameter of adipocytes in adipose tissue, the concentration of glycerol, and the expression of PPARγ and perilipin mRNA and protein. Our results show that apelin-13 can affect the metabolism of adipose tissue, inhibit adipogenic differentiation of adipocytes, promote lipolysis, and thereby improve obesity. The mechanism may be regulating the expression of PPARγ to inhibit adipogenic differentiation and regulating the expression of perilipin to promote lipolysis. This study helps us understand the role of apelin-13 in adipose tissue and provide a basis for the elucidation of the regulation mechanism of lipometabolism and the development of antiobesity drugs.

Diffuse Subcutaneous Metabolic Activity in Post Bone Marrow Transplant Hodgkin Lymphoma

ABSTRACT

We present a 14-year-old adolescent boy with Hodgkin lymphoma. He had prior completed chemotherapy with ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) regimen followed by bone marrow transplantation 6 months ago. Currently, he has neither specific clinical complaint nor receiving any specific medication. Follow-up FDG PET/CT scan demonstrated diffuse increased metabolic activity in the entire body subcutaneous tissue. This finding is rarely reported in the literature and may represent an underlying active inflammatory process, most likely attributed to the received treatments. This could impair the diagnostic quality of the scan, affecting the image interpretation, and should be recognized when present.