CT findings in surgically treated focal pancreatic disease - a retrospective study.

Background: Focal pancreatitis constitutes a classic mimicker of pancreatic ductal adenocarcinoma (PDAC). Knowledge of characteristic findings in chronic and autoimmune pancreatitis (AIP) is important to avoid unnecessary surgery. Purpose: To retrospectively investigate CT (computed tomography) imaging features of AIP and chronic pancreatitis (CP) mimicking PDAC in surgically resected patients. Material and Methods: A search in the pancreatic database in our tertiary reference center was performed, and all patients undergoing pancreatic resection during the past 10 years with a final diagnosis of AIP were initially identified. Matched groups of patients with focal CP and PDAC were extracted from the same database. A control group of patients with diffuse AIP was identified from the local benign multidisciplinary team meetings. Two experienced abdominal radiologists reviewed all patients' imaging and reached a consensus decision blinded to the diagnoses. Characteristic imaging features and attenuation values were recorded. Results: A total cohort of 41 patients (14 PDAC, 15 CP, and 12 focal AIP) who underwent surgery were included, along with 15 controls with diffuse AIP and no surgery. Both benign conditions showed contrast enhancement patterns and imaging features similar to PDAC. All groups were hypoattenuating without any significant differences in enhancement patterns. Conclusion: Differentiating focal autoimmune and CP from PDAC may be challenging despite knowledge of the characteristic CT imaging findings. Further diagnostic tests such as magnetic resonance imaging, IgG4 testing, and endoscopic ultrasound with biopsy should be performed in equivocal cases.