Carbohydrate Antigen (CA 19-9) Surge: Unraveling the Enigma of Elevated Levels in the Setting of Benign Etiologies.

Carbohydrate antigen 19-9 (CA 19-9) is widely recognized as a tumor marker primarily associated with pancreatic cancer. However, its elevation in benign pancreaticobiliary conditions complicates its diagnostic utility. We present the case of a 39-year-old male with no significant medical history who presented with symptoms of abdominal pain, nausea, vomiting, and diarrhea. The initial diagnosis suggested viral enteritis, but the subsequent worsening of symptoms led to further investigation. Elevated white blood cell counts, bilirubin levels, and liver function tests prompted magnetic resonance cholangiopancreatography (MRCP), which revealed dilated bile ducts and acute cholecystitis. Following endoscopic retrograde cholangiopancreatography (ERCP), significant hemobilia was observed, raising suspicions of cholangiocarcinoma. Despite extensive investigations, including CT angiography, MRCP, and repeat ERCPs, no malignancy was detected. Remarkably, the CA 19-9 level was elevated to 904 U/mL after the initial ERCP and uptrended to 7380 U/mL. These levels, however, normalized to 13 U/mL within two weeks of discharge. While CA 19-9 is a valuable marker in the diagnosis of pancreatic cancer, its elevation in benign pancreaticobiliary conditions necessitates cautious interpretation. In our case, choledocolithasis, cholangitis, and biliary manipulation appeared to have contributed to a transiently elevated CA 19-9. Clinicians must consider the entire clinical context when evaluating elevated CA 19-9 levels to avoid misdiagnosis and ensure appropriate patient management.