[A Case of Prostate Cancer Diagnosed by the Bone Biopsy of the Right Iliac Metastatic Lesion].

A 73-year-old man was referred to our hospital because of a high prostate specific antigen (PSA) level. The PSA level at our hospital was 63.5 ng/ml. Pelvic magnetic resonance imaging (MRI) showed findings strongly suggestive of multiple pelvic bone metastases, but no obvious malignant findings in the prostate. A 12-core prostate biopsy was performed and no cancer was detected. Computed tomography and bone scintigraphy showed findings suspicious of bone metastases in the sternum, thoracolumbar spine, pelvic bone, and sacrum. Spine MRI revealed a mass in the vertebral body from the eighth thoracic vertebra to the first lumbar vertebra. A biopsy of the right iliac crest showed adenocarcinoma and was positive for PSA staining, leading to the diagnosis of multiple bone metastases of prostate cancer. Abiraterone acetate in combination with androgen deprivation was started. He received medication and radiation therapy to his sternum for pain relief. Spine MRI after 4 months showed decreased vertebral body weights and serum PSA levels were ＜0.003 ng/ml after 5 months. Seventeen months after treatment, PSA remains below 0.003 ng/ml, and the patient is currently pain-free.