林口長庚醫院 外科部 泌尿科，長庚大學
A metastatic prostate cancer presenting with a huge pelvic mass
Tzu-Chi Teng, Chien-Lun Chen, Pei-Shan Yang, Chen-Pang Hou, Yu-Hsiang Lin, Ke-Hung Tsui, Phei-Lang Chang
Division of Urology, Department of Surgery, Chang Gung Memorial Hospital,
Chang Gung University, Linkou, Taiwan
Abstract: A 71-year-old gentleman initially presented with lower urinary tract symptoms. Prostate cancer was strongly suspected by digital rectal examination and the Prostate Specific Antigen (PSA) was 745 ng/ml. But the patient lost follow-up without a transrectal ultrasound-guided biopsy. Three years later, he visited the clinic of general surgery due to a large palpable mass over his lower abdomen and a palpable mass over the left lower back. An abdominal computed tomographic (CT) scan revealed a huge tumor that occupied the entire pelvic cavity. The largest diameter of the tumor was 23 cm. There was a soft tissue tumor in the left lower back with the destruction of ischium which suggested bony metastasis. Also, lung metastases were considered due to two small 3mm and 5 mm subpleural nodules in the left lower lung. The radiological impression was a metastatic upper rectal gastrointestinal stromal tumor. A core needle biopsy was taken from the soft tissue tumor in the left lower back and suggestive of metastatic prostatic adenocarcinoma. At that time, his PSA level was 9421 ng/ml. Bone metastasis was confirmed by a bone scan study. After androgen deprivation therapy with goserelin and cyproterone acetate, the PSA level decreased to 1564 ng/ml two weeks later. The tumor size decreased to 15.5 cm three weeks later.