FDG PET imaging in a patient with primary seminoma of the prostate.

Primary seminoma of the prostate is extremely rare. We describe a case of a 35-year-old man who presented with difficulty in urinating. Physical findings were unremarkable, but a rectal examination revealed a slightly hardened prostate with a nodule in the right lobe. Blood parameters were normal; however, blood chemistry revealed slightly elevated lactic dehydrogenase, and microscopic hematuria was evident. Serum prostate acid phosphate, carcinoembryonic antigen, and alpha-fetoprotein values were within normal limits. Both computed tomography and magnetic resonance images revealed a large mass in the prostate gland. A prostatic sarcoma or malignant lymphoma was initially suspected. A systemic survey using 18-fluoro-2-deoxyglucose (F-18 FDG) positron emission tomography revealed focal FDG uptake in the prostate gland. A prostatic biopsy of the mass was histologically diagnosed to reveal an extragonadal seminoma.