18F-PSMA-1007 Uptake in Paget Disease of the Bone: An “Iron Man” Sign

Abstract

18 F-PSMA is a promising tracer for both staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the benign pathological conditions. We report a case of 81-year-old man with a known case of prostate cancer who underwent 18 F-PSMA for restaging. 18 F-PSMA PET/CT shows intense tracer uptake in the frontal bone appearing like an "Iron Man" sign. Corresponding noncontrast CT images, pagetoid changes with thickened cortex, mixed lytic/sclerotic mottled pattern. It is important to recognize 18 F-PSMA expression in the benign nonprostatic pathologies to avoid false interpretation.

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

“…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. 17 To the best of our knowledge, we report the first case of repeated markedly increased 18 F-PSMA-1007 uptake in LHIS, another potential site of unspecific 18 F-PSMA-1007 uptake not related to prostate tissue, besides the well-known mostly benign unspecific bone uptake, 18 various benign disorders, [19][20][21][22][23][24][25][26][27][28] physiological uptake in different organs, 29 and uptake in other lipomatous benign or malignant tumors. 30,31 Although the exact uptake mechanism of 18 F-PSMA-1007 and 18 F-FDG in LHIS remains unclear, accurate analysis of the CT should be performed in cases of increased tracer uptake in the interatrial septum to rule out metastatic disease or lipomatous malignancies and confirm the diagnosis of an LHIS.…”

Hemangioma of the Ilium Simulating Bone Metastasis on 18F-PSMA-1007 PET/CT

“…1,2,5,6 There are a few case reports of 68 Ga-PSMA uptake in vertebral [7][8][9] and skull 10 hemangiomas, which may be due to PSMA expression in endothelial cells. Lowto-moderate PSMA uptake has been shown in many other benign bone lesions, including osteophyte, 11 Schmorl node, 12 fracture, 13 osteoid osteoma, 14 Paget disease, 15 fibrous dysplasia, 16 and infection. 17 Correlative anatomic imaging and PSMA PET may be especially helpful for discriminating benign bone lesion from metastatic prostate adenocarcinoma in equivocal cases.…”

Paget Disease as Common Pitfall on PET with Different Radiopharmaceuticals in Oncology: Not All That Glitters Is Gold!

“…Prostate-specific membrane antigen (PSMA) is a molecule expressed in a high variety of human tissues, and PET/CT with the PSMA ligand, labelled with both 18 F and 68 Ga, is usually used for the assessment of patients with prostate cancer. PSMA expression in non-prostatic tumor lesions has been described and is thought to be related to its overexpression in the endothelial cells of neovasculature of neoplastic and non-neoplastic conditions, stimulated by angiogenetic factors [10,13,[32][33][34][35]. However, another alternative hypothesis to explain such uptake is that PSMA accumulation may be driven by hyperemia and the subsequent increased delivery of the radiopharmaceutical [33,35].…”

“…PSMA expression in non-prostatic tumor lesions has been described and is thought to be related to its overexpression in the endothelial cells of neovasculature of neoplastic and non-neoplastic conditions, stimulated by angiogenetic factors [10,13,[32][33][34][35]. However, another alternative hypothesis to explain such uptake is that PSMA accumulation may be driven by hyperemia and the subsequent increased delivery of the radiopharmaceutical [33,35]. Similar to what was previously underlined for [ 18 F]FDG, incidental findings related to the presence of PD have been reported by radiolabeled-PSMA PET, with variable degrees of radiopharmaceutical uptake [10][11][12][13]27,[33][34][35][36][37].…”

“…However, another alternative hypothesis to explain such uptake is that PSMA accumulation may be driven by hyperemia and the subsequent increased delivery of the radiopharmaceutical [33,35]. Similar to what was previously underlined for [ 18 F]FDG, incidental findings related to the presence of PD have been reported by radiolabeled-PSMA PET, with variable degrees of radiopharmaceutical uptake [10][11][12][13]27,[33][34][35][36][37]. Interestingly, it has been suggested that PSMA expression is related to bone formation and repair and that uptake of PD at PET imaging is associated with increased bone remodeling and vascularization [11,12].…”