Secondary syphilis presenting with elevated CA19-9: A report of two cases

Syphilis is known for its diverse and often deceptive clinical manifestations, yet its potential to elevate tumor markers such as carbohydrate antigen 19-9 (CA19-9) remains underrecognized. We report two cases of secondary syphilis, each presenting with markedly elevated CA19-9 levels in the absence of malignancy. Both patients exhibited cholestatic liver enzyme elevations, and neither had structural abnormalities in the pancreaticobiliary system. In both cases, CA19-9 levels normalized following appropriate antibiotic treatment for syphilis. These cases suggest that systemic inflammation, hepatocellular injury with regenerative changes, and epithelial damage associated with syphilitic hepatitis may contribute to transient CA19-9 elevation.