[A case of prostate cancer diagnosed pathologically by bone metastatic site biopsy]

A 61-year-old man consulted our hospital complaining of high prostate specific antigen (PSA) value and difficulty to urinate. Prostate biopsy had been performed at another hospital, but did not reveal cancer. PSA was 18.5 ng/ml. Transrectal ultrasound-guided prostate biopsy was performed, but cancer was not detected. Later, PSA rose rapidly, and findings suggesting bone metastasis at right pubic bone and left sacro-ilial joint were found on computed tomography (CT), bone scintigraphy and magnetic resonance imaging (MRI). A repeat prostate biopsy was performed, but cancer was not detected from the prostate. On right pubic bone biopsy, poorly to moderately differentiated adenocarcinoma was detected. PSA immunohistochemical staining was positive, and the diagnosis was bone metastasis from prostate cancer. After endocrine therapy was started, PSA declined and bone metastasis disappeared on bone scintigraphy.