Periampullary diverticulitis (Lemmel's syndrome) misdiagnosed as pancreatic head tumor: A report of two cases

INTRODUCTION AND IMPORTANCE: Lemmel's syndrome is a rare condition caused by a periampullary duodenal diverticulum that compresses the ampulla, causing jaundice. Two cases of misdiagnosis as pancreatic tumors are presented, both confirmed as Lemmel's syndrome with MRCP. Conservative therapy is the main treatment, with invasive procedures reserved for rare cases. CASE PRESENTATION: Case 1: An 82-year-old patient presented with abdominal pain, vomiting, fever, weight loss, and jaundice. MRCP showed a pancreatic head tumor, but multiple scans and procedures confirmed the diagnosis of Lemmel's syndrome caused by a periampullary duodenal diverticulum. Case 2: A 48-year-old patient had abdominal pain, vomiting, temperature, acholic feces, and jaundice. MRI with MRCP suggested a pancreatic tumor, and the patient underwent ERCP, papillotomy, and biliary stent placement. However, after three failed stent changes, MRCP revealed Lemmel's syndrome. CLINICAL DISCUSSION: Lemmel's syndrome can be diagnostically challenging for physicians as it mimics pancreatic tumors. MRCP is the primary diagnostic tool, and conservative therapy is the primary treatment, with invasive procedures being uncommon. CONCLUSION: Consider Lemmel's syndrome as a possible differential diagnosis in obstructive jaundice cases. Comprehensive diagnostic methods and repeated imaging are crucial to prevent misdiagnosis. Early detection and appropriate treatment can improve patient outcomes.