Solid pseudopapillary tumour should be part of differential diagnosis of focal pancreatic lesions with increased ¹⁸F‐FDOPA uptake

Abstract

Objective To assess the specificity of increased 18F‐dihydroxyphenylalanine (18F‐FDOPA) uptake in patients who underwent PET/CT for suspicion of isolated pancreatic neuroendocrine tumour (pNET). False‐positive results mimicking a pNET have been investigated. Material and methods Carbidopa‐assisted 18F‐FDOPA PET/CT scans performed in patients with suspicion of localized pNET were retrieved. Only patients with a definitive diagnosis were retrospectively included. When available, the histopathological result after pancreatic surgery was the gold standard. In other cases, the diagnosis was based on endoscopic ultrasonography (EUS)/cytology and/or on concordant imaging results of at least two of the following: contrast‐enhanced computed tomography (CE‐CT), magnetic resonance imaging (MRI) and somatostatin receptor scintigraphy (SRS). Results Forty‐four among 731 patients were selected. Among these, 36 patients (82%) were surgically treated, revealing pNET (n = 28), solid pseudopapillary tumour (SPT) (n = 4), adenocarcinoma (n = 2), serous cystadenomas (n = 1) and solitary fibrous tumour (n = 1) cases. An additional three cases of pNET were diagnosed by EUS/cytology. In the remaining five patients, a consensus was reached on follow‐up imaging results: pNET (n = 1), serous cystadenoma (n = 2) and undetermined/no pNET (n = 2). Both specificity and negative predictive value of 18F‐FDOPA PET/CT for localized pNET were 67%. Surprisingly, all four false‐positive results were SPTs showing intense 18F‐FDOPA uptake and negative SRS. There was no significant difference in 18F‐FDOPA uptake intensity between PET‐positive pNETs and SPTs. Conclusion 18F‐FDOPA PET/CT is not specific for pNET in patients with localized pancreatic lesions. SPT could mimic pNET and should be part of differential diagnosis in such a clinical situation. If these results are confirmed in a broader population, the imaging pattern 18F‐FDOPA PET‐positive/SRS‐negative lesions might be considered as the imaging phenotype of SPT.

Age in combination with gender is a valuable parameter in differential diagnosis of solid pseudopapillary tumors and pancreatic neuroendocrine neoplasm

“…The 18 F-FDOPA PET-positive/SRS-negative lesions might be the SPTs. However, these should be verified in a large cohort [ 21 ]. EUS-FNB might be another promising diagnostic tool for distincitng SPTs from PNENs [ 24 , 25 ].…”

“…Notably, both SPTs and cystic endocrine tumors have the same features, such as areas of cystic change, enhancing components, and well-defined contours [20]. Although positron emission tomography/computed tomography (PET/CT) is widely used in the diagnosis of malignant tumors and pancreatic disease, there are very few studies that evaluated the accuracy of PET/CT in the diagnosis of SPTs [21][22][23]. François et al reported that 18 F-FDOPA PET/CT was a promising approach for the diagnosis of pNENs and SPTs.…”

Urinary free cortisol: An automated immunoassay without extraction for diagnosis of Cushing’s syndrome and follow‐up of patients treated by anticortisolic drugs

“…3,4 ) In order to estimate the potential impact of modified steroidogenesis on UFC measurements, 2 groups of samples were studied. Group As underlined by Oβwald et al, 5 In conclusion, a fast and reliable method for UFC measurements improves patient care, allows day-to-day treatment adjustment and therefore shortens the length of hospital stay.…”

Pancreatic neuroendocrine neoplasms — update of the diagnostic and therapeutic guidelines (recommended by the Polish Network of Neuroendocrine Tumours) [Nowotwory neuroendokrynne trzustki — uaktualnione zasady diagnostyki i leczenia (rekomendowane przez Polską Sieć Guzów Neuroendokrynych)]

“…When available, mainly in specialised centres, molecular imaging with [ 18 F] F-DOPA can be applied using labelled analogue for the GLP-1 receptor [ 11 C]C-methionine [93]. Imaging with [ 18 F] F-DOPA, in accordance with the 2017 European Association of Nuclear Medicine (EANM) guidelines, is not recommended in PanNET due to the potential risk of false positives in non-neuroendocrine pancreatic neoplasms, such as pancreatic pseudopapillary tumour, and pancreatic serous cystadenoma [94,95].…”