Differentiation of autoimmune pancreatitis from suspected pancreatic cancer by fluorine-18 fluorodeoxyglucose positron emission tomography.
BACKGROUND
Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been widely used for the diagnosis of pancreatic cancer. Because autoimmune pancreatitis is easily misdiagnosed as pancreatic cancer and can be tested for by FDG-PET analysis based on the presence of suspected pancreatic cancer, we attempted to clarify the differences in FDG-PET findings between the two conditions.


METHODS
We compared FDG-PET findings between 15 patients with autoimmune pancreatitis and 26 patients with pancreatic cancer. The findings were evaluated visually or semiquantitatively using the maximum standardized uptake value and the accumulation pattern of FDG.


RESULTS
FDG uptake was found in all 15 patients with autoimmune pancreatitis, whereas it was found in 19 of 26 patients (73.1%) with pancreatic cancer. An accumulation pattern characterized by nodular shapes was significantly more frequent in pancreatic cancer, whereas a longitudinal shape indicated autoimmune pancreatitis. Heterogeneous accumulation was found in almost all cases of autoimmune pancreatitis, whereas homogeneous accumulation was found in pancreatic cancer. Significantly more cases of pancreatic cancer showed solitary localization, whereas multiple localization in the pancreas favored the presence of autoimmune pancreatitis. FDG uptake by the hilar lymph node was significantly more frequent in autoimmune pancreatitis than in pancreatic cancer, and uptake by the lachrymal gland, salivary gland, biliary duct, retroperitoneal space, and prostate were seen only in autoimmune pancreatitis.


CONCLUSIONS
FDG-PET is a useful tool for differentiating autoimmune pancreatitis from suspected pancreatic cancer, if the accumulation pattern and extrapancreatic involvement are considered. IgG4 measurement and other current image tests can further confirm the diagnosis.
Ozaki
Yayoi
Y
Department of Medicine, Gastroenterology, Shinshu University School of Medicine, Matsumoto, Japan.
Oguchi
Kazuhiro
K
Hamano
Hideaki
H
Arakura
Norikazu
N
Muraki
Takashi
T
Kiyosawa
Kendo
K
Momose
Mitsuhiro
M
Kadoya
Masumi
M
Miyata
Kazunobu
K
Aizawa
Takao
T
Kawa
Shigeyuki
S
D000230:Adenocarcinoma / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D010195:Pancreatitis / Q000000981:diagnostic imaging* / Q000276:immunology; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18