Comparison between groove carcinoma and groove pancreatitis.

BACKGROUND/OBJECTIVES: The pancreatoduodenal groove (anatomical groove) is a potential space bordered by the head of the pancreas, duodenum, and common bile duct. Discerning between groove carcinoma (GC) and groove pancreatitis (GP) is often difficult, but clinically important. We retrospectively analyzed and compared the findings of computed tomography (CT), laboratory tests, and endoscopic ultrasound-fine needle aspiration (EUS-FNA) for GC and GP.

METHODS: GC (n = 36) and GP (n = 44) patients at Asan Medical Center from January 1, 2000, to May 31, 2017 were retrospectively reviewed. MDCT findings, baseline characteristics, laboratory test results, and EUS and EUS-FNA findings of GC and GP patients were compared.

RESULTS: CT showed no significant difference in groove enhancement between the groups. Mass-like lesions, cystic groove lesions, and calcification were observed in 86.1% and 15.9%, 38.9% and 75%, and 2.8% and 29.5% of GC and GP patients, respectively. Patients were tested for total bilirubin (GC: 2.0 vs. GP: 0.6 mg/dL), cancer antigen 19-9 (CA19-9) (GC: 76 vs. GP: 12.5 U/mL), and carcinoembryonic antigen (GC: 2.4 vs. GP: 2 ng/mL). Three GP patients died, and one GP patient was diagnosed with GC. However, among 30 GC patients with at least 1-year follow-up, 20 died. In multivariate logistic regression, CA19-9, and mass-like lesion on multidetector CT (MDCT) were discriminating factors between GC and GP. Among 23 (10 GC, 13 GP) patients who underwent EUS-FNA, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value, accuracy of EUS-FNA were 90%, 100%, 100%, 92.86%, and 95.65%, respectively.

CONCLUSIONS: Several MDCT and laboratory findings favor GC over GP. EUS-FNA should be considered in patients with elevated CA19-9 levels and mass-like lesions on MDCT.