Elevated carcinoembryonic antigen and sarcoidosis masquerading as metastatic colon cancer.

When patients with colorectal cancer are monitored after resection of primary or metastatic disease, an elevated carcinoembryonic antigen (CEA) level is usually an indicator of recurrent disease. Positron emission tomography (PET) scans are often used to locate the site of recurrences when computed tomography scans do not show the presence of disease. This case highlights an important cause of a falsely elevated CEA with abnormal PET imaging.