Elevated carcinoembryonic antigen (CEA) levels in a patient with no malignancy.

Carcinoembryonic antigen rarely exceeds serum levels of 10-12 ng/mL in benign diseases and has never been found above 24 ng/ml. We report a case in which carcinoembryonic antigen serum levels reached the value of 44.9 ng/ml without any overt reason (after 22 months of follow-up). A decline of the carcinoembryonic antigen to normal ranges was noticed after a radiolabeled anti-carcinoembryonic antigen monoclonal antibody scan was performed. The reason for this phenomenon is unclear.