S3569 The Phantom Obstruction: Lemmel Syndrome Causing Recurrent Cholangitis Without Stones

Introduction: Lemmel syndrome is a rare cause of obstructive jaundice due to extrinsic compression of the common bile duct by a periampullary duodenal diverticulum, occurring in the absence of stones or malignancy. Although duodenal diverticula are common, only a small fraction are periampullary and symptomatic. Diagnosis is often incidental, as clinical signs are nonspecific and frequently mimic pancreatic or biliary tumors. Magnetic resonance cholangiopancreatography (MRCP) is useful for non-invasive evaluation, while endoscopic retrograde cholangiopancreatography (ERCP) remains the gold standard for both diagnosis and treatment. Management is individualized due to its rarity and variable presentation. We present a rare case of Lemmel syndrome presenting with recurrent cholangitis and intermittent jaundice, emphasizing the need for high clinical suspicion in similar scenarios. Case Description/Methods: A 50-year-old man with no prior comorbidities presented with intermittent, colicky epigastric pain for 1 year, aggravated postprandially and occasionally associated with fever. Initial evaluation showed cholestatic injury-transaminitis (ALT 464 U/L, AST 664 U/L), elevated ALP (270 U/L), total bilirubin 1.8 mg/dL, and lipase 137 U/L. Abdominal ultrasound was unremarkable. Contrast-enhanced computed tomography revealed a distal extrinsic compression with evidence of a periampullary diverticulum. MRCP confirmed a periampullary duodenal diverticulum compressing the common bile duct (CBD), consistent with Lemmel syndrome. Initial ERCP failed to achieve biliary stenting; only papillotomy was performed. The patient showed temporary clinical improvement. He later developed scleral icterus and recurrent cholangitis, with worsening liver function tests (peak bilirubin 5.7 mg/dL). Repeat ERCP revealed a dilated CBD, tortuous cystic duct with low insertion. Selective cannulation was achieved, and a biliary stent was successfully placed. Post-procedure, the patient had marked clinical and biochemical improvement and remained asymptomatic on follow-up. Discussion: This case illustrates Lemmel syndrome as a rare cause of recurrent cholangitis and highlights repeat ERCP as a viable non-surgical treatment option when performed by experienced endoscopists familiar with altered periampullary anatomy. It is a rare cause of obstructive jaundice due to periampullary duodenal diverticulum compressing the CBD. It should be considered when imaging shows no stones or tumors. Diagnosis requires high suspicion and advanced imaging. ERCP offers both diagnosis and treatment. Increased awareness is key to avoiding misdiagnosis and unnecessary surgery.