PSA measurement following prostatectomy: an unexpected error.

An unexpected and exceptional observation was made during the biological follow-up of a patient who had undergone a radical prostatectomy for a prostate adenocarcinoma. A residual PSA level was first considered as a reliable marker of relapse. Certain limits are highlighted concerning the reliability of the PSA assay, which must be interpreted along with all the other prognostic information on the tumor and possibly verified using other biological techniques.