Introduction:

Fibrosis is commonly used as the criterion standard for diagnosing chronic pancreatitis (CP). However, there has never been a study comparing fibrosis among patients with recurrent acute pancreatitis (RAP) and CP.

Materials and methods:

Patients undergoing total pancreatectomy with islet autotransplantation (TPIAT) between 2011 to 2023 were classified into 3 groups: Definite CP by M-ANNHEIM criteria (n=34); RAP, ≥2 episodes of imaging documented acute pancreatitis (n=37); and indeterminate CP (n=17) as chronic abdominal pain with two or more of the following: Endoscopic ultrasound (EUS) > 5 criteria , ductal or parenchymal abnormalities on MRI/MRCP, and/or secretin endoscopic pancreatic function testing (ePFT) with a bicarbonate concentration of <80 mmol/L at 60 min. Excisional biopsies obtained at the time of TPIAT from the proximal and distal portions of the pancreas were evaluated to calculate a fibrosis score (FS). The FS consists of both focal/diffuse and perilobular/intralobular fibrosis with scores of 1-6 for each component, with 6 being the most severe. Total FS was calculated by summing up the average perilobular and intralobular FS from excisional biopsies of head and body/tail regions. A one-way ANOVA was utilized to compare FS among the 3 groups with pairwise comparisons evaluated using the Tukey post-hoc test.

RESULTS:
88 patients were evaluated for this study with a mean age 38±14 years and 46 (52.3%) were female. Genetic (52.3%) and idiopathic (37.5%) were the most common risk factors for pancreatitis. The mean duration of disease was 8 ± 7 years. There were no significant differences between the 3 groups in age, gender, BMI, duration of disease and diabetes status. Mean FS was 3±2.8; 6.6±3, and 8.7±2.9 in indeterminate CP, RAP, and definite CP, respectively. There was a statistically significant difference between the 3 groups as determined by one-way ANOVA [F (2,85)=87, p<0.0001]. The mean FS was significantly higher in the definite CP compared to RAP and indeterminate CP[all p<0.001]. The mean FS in RAP was significantly higher than the indeterminate. Out of the 17 indeterminate CP patients, 4 had abnormal endoscopic pancreatic function tests, 5 had >=5 EUS criteria, 6 had reduced T1 signal intensity on MRI, and 6 had ductal abnormalities on MRCP.

Conclusion:

Indeterminate CP patients have significantly lower FS compared to both those with imaging documented RAP and definite CP by M-ANNHEIM. Current diagnostic criteria for indeterminate CP requires modification if fibrosis is the criteria standard for CP.

Figure 1: Comparison of FS in Indeterminate CP, RAP and Definite CP. Values are reported as mean +/-s.d.

Rifat Mannan

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