Prostatic carcinoma with elevated carcinoembryonic antigen: a case report.

Carcinoembryonic antigen is a glycoprotein often associated with colorectal carcinoma but can also increase in other malignancies. We reported a rare case of prostate mucinous adenocarcinoma in a 69-year-old male with elevated carcinoembryonic antigen and normal prostate-specific antigen. The patient, with a history of benign prostatic hyperplasia, was initially asymptomatic apart from an elevated carcinoembryonic antigen detected during routine examination. Comprehensive evaluations, including colonoscopy, CT and PET/CT, yielded no conclusive findings. However, a pelvic MRI later revealed an irregular prostatic mass, and a biopsy confirmed adenocarcinoma with mucinous features. Carcinoembryonic antigen positivity was further demonstrated by immunohistochemistry on the specimen. This case highlights that isolated carcinoembryonic antigen elevation, even in the absence of prostate-specific antigen elevation, may warrant consideration of prostatic carcinoma in differential diagnosis, particularly in the absence of colorectal carcinoma history. Elevated carcinoembryonic antigen levels should prompt further investigation, as they may serve as an early marker for prostatic malignancies when followed by targeted imaging and histological confirmation.