[A Case of Prostate Cancer with High Levels of Prostate-Specific Antigen Undetected by Prostate Biopsy].

: A 79 year-old-man visited our hospital with right back pain. Computed tomography suggested external iliac and para-aortic lymphadenopathy. Serum prostate specific antigen (PSA) increased to 335 ng/ml and prostate cancer was highly suspected. We performed transperineal prostate biopsies two times, but could not detect prostate carcinoma cells. Multiparametric magnetic resonance imaging (MRI) indicated no suspicious malignant lesions in the prostate. Laparoscopic biopsy of the right obturator lymph nodes was performed and histological examination, including immunohistochemical staining with PSA, confirmed lymphnode metastasis from prostate cancer. After endocrine therapy was started, serum PSA levels declined and lymph nodes shrunk. In cases of negative prostate biopsies despite high serum PSA levels, aggressive indication for biopsy of metastatic lesion and histological inspection is highly recommended.