When Recurrent Pancreatitis Is Not Pancreatitis: Cyclic Vomiting Syndrome Masquerading as Acute Pancreatitis in a Young Adult.

Recurrent acute pancreatitis in young adults usually triggers an extensive evaluation for structural, genetic, metabolic, autoimmune, or toxic etiologies. However, pancreatic enzyme elevation and radiologic changes may occasionally arise from extra-pancreatic mechanisms, leading to diagnostic anchoring. We report a 20-year-old male who experienced four discrete episodes over a year, initially diagnosed as acute pancreatitis based on abdominal pain, vomiting, marked lipase elevation, and computed tomography findings. Each episode followed a highly stereotyped pattern beginning with prodromal uneasiness, progressing to repetitive vomiting, severe abdominal pain, diarrhea, and a post-episode phase of constipation with complete inter-episodic recovery. Subsequent attacks reproduced identical symptoms despite normal to mildly elevated pancreatic enzymes and imaging. The patient also reported recurrent sinus congestion, headaches, and muscle cramps, with a strong family history of migraine. An extensive evaluation, including heavy metal screening, autoimmune and immunologic testing, IgG4 levels, celiac serology, calcium and parathyroid hormone levels, ceruloplasmin, iron indices, cystic fibrosis transmembrane conductance regulator (CFTR) gene analysis, and porphyria testing, was unrevealing. Upper gastrointestinal endoscopy performed shortly after one attack demonstrated proximal gastric congestion without erosions or ulceration. Careful reconstruction of the clinical chronology revealed a classic four-phase cyclic pattern consistent with cyclic vomiting syndrome (CVS) within the abdominal migraine spectrum. Initiation of migraine-oriented prophylaxis with topiramate resulted in a marked reduction in attack frequency and severity. This case highlights how CVS can masquerade as recurrent pancreatitis and underscores the importance of recognizing neuro-visceral patterns in patients with recurrent vomiting and abdominal pain, even in the presence of transient pancreatic enzyme elevation.