Diffuse Echogenicity on Endoscopic Ultrasound is a Common and Dynamic Entity Amongst Patients With Acute Recurrent Pancreatitis: A Single-Center Retrospective Study

Introduction: Determining the etiology of acute recurrent pancreatitis (ARP) remains challenging despite advances in diagnostic modalities. Fatty replacement of the pancreatic parenchyma is a result of acinar cell necrosis in acute pancreatitis (AP), but also has been shown to be a risk factor for developing AP. Thus, it is unclear whether fatty pancreas (FP) is a cause or consequence of acute pancreatitis and its presence predicts ARP. The aim of this study is to assess the prevalence of FP in patients with ARP, focusing on changes over time. Methods: Patients who underwent endoscopic ultrasound (EUS) for evaluation of ARP from 2015 to 2022 at a tertiary center in the US were included. FP on EUS was defined as presence of diffuse echogenicity within the pancreatic parenchyma. Patients’ demographics, clinical data, and EUS findings were collected retrospectively. Results: Overall, 50 patients were included (54% female) with a mean age of 47.9 ± 14.7 years and mean body mass index (BMI) of 30.8±7.8 kg/m2 (Table 1). The most common etiology of ARP was undetermined in 60% of patients, followed by gallstones and hyperlipidemia in 10% of patients each. On initial EUS, 44 patients had FP (88%). The average number of pancreatitis episodes prior to index EUS was 2.8±2.6, without a significant difference between those with and without FP (P=0.14). Overall, 7 patients had exocrine insufficiency (39%), with no significant difference between patients with and without FP (36% vs 50%, P= 0.30). Fatty liver was noted in 45% of patients with FP. Pseudocysts and necrotizing pancreatitis were seen more in patients without FP. Follow up EUS was performed in 16 patients (average 483±362 days). Of the 11 patients with FP on index EUS, progression to chronic pancreatitis was noted in 45.5% (n=5), resolution of FP in 36.4% (n=4) and persistent FP in 18.2% (n=2). New FP was evident in 80% (4/5) patients without FP on the index EUS. There was no significant trend in weight amongst the various patterns of FP changes over time (P=0.309) (Figure 1). Of the 11 patients who had an EUS prior to their index EUS, 5 had FP with persistent FP on the index EUS, and 3 had new FP on the index EUS. Conclusion: FP on EUS preceded ARP episodes in 11.4% and de novo FP was noted in 80% of patients after an episode of acute pancreatitis. Fatty pancreas is a dynamic entity after acute pancreatitis with the possibility of progression or regression over time. Larger prospective trials are needed to accurately study the role of FP in ARP.Figure 1.: Trend of mean weight for patient with available follow up EUS in relation to FP appearance on follow up EUS. Table 1. - Demographic and Clinical Data for Patients With Acute Recurrent Pancreatitis Overall No fatty pancreas Fatty pancreas N or Mean % or SD N or Mean % or SD N or Mean % or SD P-value Total patients 50 6 44 Demographics Female 27 54% 4 67% 23 52% 0.86 White 41 82% 6 100% 35 80% 1.00 Hyperlipidemia 22 44% 3 50% 19 43% 0.77 Diabetes 20 40% 4 67% 16 36% 0.97 Tobacco use 18 36% 3 50% 15 34% 0.89 Alcohol use 18 36% 1 17% 17 39% 0.29 Prior cholecystectomy 32 64% 5 83% 27 61% 0.94 Age 47.9 14.7 50.5 12.7 47.5 15 0.32 Weight (kg) 91.0 27.5 78.7 14.5 92.6 31 0.12 BMI 30.8 7.8 29.7 5 28.5 8.1 0.35 Index EUS Hyperechoic strands 23 46% 3 50% 20 45% 0.74 Hyperechoic foci 16 32% 3 50% 13 30% 0.93 Lobularity 17 34% 3 50% 14 32% 0.91 Cyst 9 18% 2 33% 7 16% 0.94 Dilated pancreatic duct 8 16% 1 17% 7 16% 0.76 Irregular pancreatic duct 7 14% 0 0% 7 16% 0.38 Dilated side branch 5 10% 2 33% 3 7% 0.99 Hyperechoic duct walls 7 14% 2 33% 5 11% 0.97 Intraparenchymal calcifications 3 6% 1 17% 2 5% 0.97 Intraductal stone 1 2% 0 0% 1 2% 0.88 Atrophy 6 12% 1 17% 5 11% 0.85 Number of acute pancreatitis episodes prior to index EUS 2.8 2.6 1.7 0.5 2.9 2.8 0.14 Laboratory Data Lipase 248.4 485.6 108.0 89.1 268.0 515.1 0.23 Triglyceride 168.3 107.1 195.7 110.2 163.8 107.5 0.25 Calcium 9.2 0.7 9.5 0.8 9.1 0.7 0.10 IGG4 38.9 34.0 35.7 33.6 39.3 34.7 0.43 CA 19-9 9.1 3.5 10.5 4.7 8.5 3.1 0.18 Tbili 0.6 0.4 0.4 0.3 0.6 0.4 0.06 EPI 7 39% 2 50% 5 36% 0.86 Location Outpatient 41 82% 6 100% 35 80% 1.00 Wards 8 16% 0 0% 8 18% 0.33 ICU 1 2% 0 0% 1 2% 0.88 Fatty liver on imaging 22 44% 2 33% 20 45% 0.46 Genetic testing Positive 3 6% 1 17% 2 5% 0.97 Negative 4 8% 1 17% 3 7% 0.93 Complications Pseudocyst 12 24% 4 67% 8 18% 1.00 Necrotizing pancreatitis 4 8% 1 17% 3 7% 0.93 Etiology of pancreatitis Genetic 2 4% 0 0% 2 5% 0.77 Gallstone 5 10% 1 17% 4 9% 0.90 Autoimmune 3 6% 1 17% 2 5% 0.97 HLD 5 10% 1 17% 4 9% 0.90 Pancreas divisum 4 8% 2 33% 2 5% 1.00 Unknown 30 60% 1 17% 29 66% 0.03