Metastatic prostatic adenocarcinoma in an inguinal hernia sac in a patient with undetectable serum prostate specific antigen level.

Metastatic prostate cancer found within the hernia sac contents is a rare clinical manifestation. We report a 64-year-old male patient who presented with rare clinical features of prostate cancer. A focal metastasis of prostate cancer was incidentally found in an incised inguinal hernia sac 5 years after radical prostatectomy. The serum prostate specific antigen (PSA) level remained undetectable (<0.01 ng/mL) prior to herniorrhaphy without any adjuvant therapy. In addition, serial studies performed right after herniorrhaphy disclosed no evidence of overt clinical metastasis. However, his serum PSA level started rising 12 months later and bladder invasion as well as a mass in the cul-de-sac was identified subsequently. The serum PSA level was 2.45 ng/mL at his latest visit, which was 5 years after herniorrhaphy. This case implies that physicians should be more alert in patients with a low preoperative serum PSA level during the period of follow-up. Both serum PSA and digital rectal examination may be important in patients with low preoperative PSA level after radical prostatectomy.