## 4 Case Presentation  
A 64-year-old man presented to the emergency department in March 2019 with nausea and sudden epigastric pain, radiating to the right and left hypochondrium as well as to the back. The patient had a recent history of hospitalization for two episodes of acute pancreatitis in December 2018 and January 2019. Cholelithiasis was detected and a laparoscopic cholecystectomy was performed. The surgery had no complications, but the patient was re-admitted to the surgery department one month later for recurrence of acute on chronic pancreatitis. During this last hospitalization, an autoimmune aetiology was excluded by serologic studies including IgG4 levels. A magnetic resonance cholangiocarcinomareatography (MRCP) was performed, showing pseudocysts of the pancreas head, but no lithiasis of the common bile duct. The patient had a history of ischemic heart disease, treated with percutaneous transluminal coronary angioplasty (PTCA), arterial hypertension and type 2 diabetes. He denied alcohol intake, smoking, or a family history of pancreatic disorders. He presented with fever and on physical examination, the abdomen was tender, especially in the epigastric region; peristalsis was preserved, with no signs of peritoneal irritation. Vital parameters were stable. Blood cultures and chest X-rays were negative. Among the standard laboratory tests performed, C reactive protein (CRP), lipase, and amylase levels were elevated at 4.4 mg/dL (normal value < 0.7 mg/dL), 385 U/L (n.v. < 60 U/L), and 480 U/L (n.v. < 100), respectively. Aminotransferase (AST), alanine aminotransferase (ALT), bilirubin, \(\gamma\)-glutamyl transferase (GGT) and alkaline phosphatase (ALP) were normal, as was his lipid profile. White blood cells (WBC) were 10,700 cells/\(\mu\)L, hemoglobin 10.4 mg/dL. Creatinine, calcium, and electrolytes levels were normal. During the hospital stay, in-depth blood tests were performed, showing normal values of chromogranin A, parathyroid hormone (PTH), immunoglobulin, antinuclear antibodies (ANA), antimitochondrial antibodies (AMA), anti-smooth muscle antibodies (ASMA), carcinoembryonic antigen (CEA), and carbohydrate antigen 19.9 (CA-19.9). The patient was therefore admitted to the surgery department with the diagnosis of idiopathic recurrent acute on chronic pancreatitis and received supportive care. Contrastenhanced computed tomography (CECT) and MRCP both revealed the presence of effusion near the stomach, liver, spleen, and left colon; pseudocysts appeared less prominent than in the previous MRCP. [PERSON]'s duct and the bile ducts had normal diameters, without filling defects. EUS showed inflammation of the pancreatic parenchyma, characterized by hyperechoic foci with shadowing, stranding and lobularity with honeycomb, associated with thickening and spontaneous bleeding of the duodenal wall; in addition, some hypoechoic echotexture was observed in the head and body of the pancreas, supporting the CECT and MRCP findings of multiple fluid collections with liquefactive necrotic areas, indicating superinfection. Fifteen days after antibiotic treatment, MRCP revealed a significant reduction of the effusions previously detected, but the appearance of 23 mm parenchymal necrosis, resulting in a centimetric interruption of the pancreatic duct at the pancreatic head, with the duct reappearing at the minor papilla, communicating with a thin collection arranged in an annular fashion along the duodenal wall (Figure 3). The pseudocyst formations were unchanged along the hepatic profile and in the peri-pancreatic regions. These findings are strongly suggestive of pancreas divisum (Figure 4), with signs of active inflammation, abdominal pseudocysts and fistulous tracts between the minor papilla and the duodenal wall.