Intermittent FDG Uptake in Lipomatous Hypertrophy of the Interatrial Septum on Serial PET/CT Scans

Abstract

We present a unique case of a patient with a clinical history of distal esophageal carcinoma and CT appearance of lipomatous hypertrophy of the interatrial septum who displayed fluorine-18-fluorodeoxyglucose (FDG) uptake in the interatrial septal fat on only the second of 4 serial PET/CT studies. As PET/CT scans are used for the initial staging of esophageal carcinoma, one should not mistake more benign causes of mediastinal uptake for metastasis when observing an intermittent pattern of uptake on a PET/CT scan.

FDG Uptake in Lipomatous Hypertrophy of the Interatrial Septum Is Not Likely Related to Brown Adipose Tissue

“…In a series consisting of 23 patients with increased FDG uptake in LHIS, none of the patients were reported to have concurrent uptake in BAT elsewhere. 7 In addition, in another case of a 69-year-old man with esophageal cancer who had a series of FDG PET/CT studies demonstrating variable FDG uptake by LHIS, 9 there was no evidence of concurrent increased FDG uptake by BAT elsewhere.…”

“…Increased FDG uptake in LHIS has occasionally been found on PET or PET/ computed tomography (CT). [7][8][9] It has been postulated that metabolically active BAT in LHIS is responsible for increased FDG uptake. 7,8 Interestingly, none of the cases reported in the literature show concurrent increased FDG uptake by BAT in typical locations elsewhere in the body, eg, cervical, supraclavicular, mediastinal, paravertebral regions.…”

The Importance of Recognizing Hibernomas as Possibly Not So Rare Pitfalls in FDG PET—A Histologically Verified Case and Literature Review

“…The site of uptake is no aid in differential diagnosis as beside the most common anatomic locations (neck, muscles, mediastinum, retroperitoneum… [4]) hibernomas may occur virtually everywhere. Unusual sites as the heart [5][6][7] and the breast [8] have been reported. Differential diagnosis to liposarcoma is difficult though these normally show low to intermediate metabolic activity in contrast to the high FDG uptake of hibernoma, but a considerable overlap exists [9][10][11].…”

Increased 18F-PSMA and 18F-FDG Uptake in Lipomatous Hypertrophy of the Interatrial Septum

“…4,5 Although LHIS is a benign disorder and remains asymptomatic in the majority of cases, it rarely can cause atrial arrhythmias, obstructive flow symptoms, and sudden death. [6][7][8][9][10][11][12][13] Increased 18 F-FDG uptake in LHIS can occasionally be found on 18 F-FDG PET/CT, 14,15 initially thought to be caused by metabolic activation of brown adipose tissue. 16 There is no evidence of increased 18 F-FDG uptake in other brown adipose tissue in our patient, and this theory has also been questioned by some authors, suggesting inflammation or other unknown mechanism of increased 18 F-FDG uptake.…”