[A case of prostate cancer that developed following transurethral resection of the prostate: diagnostic efficiency of diffusion-weighted images on magnetic resonance imaging].

An 84-year-old man underwent transurethral resection of the prostate (TURP) with a diagnosis of prostatic hypertrophy at the age of 78. He had a moderately high prostate specific antigen (PSA) level of 4.5 ng/ml before TURP, but without pathological malignancy. Following surgery, his PSA level dropped to 1.7 ng/ml and the patient recovered almost completely. Four years later, however, he underwent a reexamination due to diminished urinary flow. His PSA at that time was 5.2 ng/ml, continuing to rise slowly thereafter. Six years following surgery, his PSA reached 13.7 ng/ml, and the diffusion-weighted image on magnetic resonance imaging showed a high intensity area in the prostatic portion of the urethra. A poorly differentiated adenocarcinoma was detected in TUR-derived tissue fragments of the tumor protruding from the prostate. Tissue obtained via a systematic needle biopsy showed no signs of malignancy. Hormonal therapy was introduced. Five months later, the PSA level fell to 0.130 ng/ml ; the patient is now in clinical follow-up.