Prostate cancer with cyst formation detected by whole body positron emission tomography/computed tomography: A case report

The present study reports a case of prostate adenocarcinoma with cyst formation. A 72-year-old male diagnosed with multiple lung metastases at a local clinic was referred to Tokai University Hachioji Hospital (Tokyo, Japan) for detection of a primary lesion. Whole body positron emission tomography/computed tomography showed strong accumulation of [(18)F]-fluoro-deoxy-2-glucose (FDG) in the small pelvis, and pelvic magnetic resonance imaging revealed a 60×40-mm cystic lesion, with an irregular thickened wall, behind the prostate. The serum prostate-specific antigen (PSA) level was elevated to 211.99 ng/ml, therefore, the patient underwent a transperineal prostate needle biopsy, and was diagnosed with prostate adenocarcinoma with cyst formation. Androgen deprivation therapy was administered for 8 months following the diagnosis of prostate cancer; consequently, the cyst reduced in size and the serum PSA level decreased to 0.14 ng/ml. To the best of our knowledge, this is the first report of a malignant prostatic cyst detected by FDG-positron emission tomography/computed tomography.