A rare culprit: Acute pancreatitis associated with anisakiasis

Acute pancreatitis is an uncommon but clinically significant manifestation of food allergy. We describe the case of a 72-year-old man with diabetes and hypertension who developed acute abdominal pain three hours after consuming raw flounder. On admission, laboratory testing demonstrated leukocytosis, markedly elevated serum amylase (807 U/L) and urinary amylase (12,428 U/L). Imaging studies revealed diffuse pancreatic edema and surrounding fat stranding consistent with acute pancreatitis. Importantly, the patient had no history of gallstones, alcohol consumption, or structural biliary abnormalities. A remarkable elevation in Anisakis-specific IgE (76 Ua/mL; reference <0.34) and total IgE (572 IU/mL; reference <170) strongly implicated an allergic mechanism. He was treated conservatively with fasting and intravenous fluids, and his symptoms gradually improved. Following strict avoidance of raw fish, his IgE levels showed a marked decline and there was no recurrence of pancreatitis for over a year. Interestingly, his long-standing chronic urticaria also improved markedly with dietary modification. This case highlights the importance of considering Anisakis-induced allergy in the differential diagnosis of idiopathic acute pancreatitis, particularly in countries with high raw fish consumption. Serological testing for Anisakis-specific IgE can provide a valuable diagnostic clue, and dietary counseling may prevent recurrence. Greater awareness of this rare but important etiology is warranted among clinicians worldwide. Infectious etiologies, such as mumps, viral hepatitis, and scrub typhus, as well as autoimmune pancreatitis, were considered but excluded based on clinical presentation, laboratory findings, and absence of relevant risk factors in this patient.