A 65-year-old man presents to the clinic with lower back pain, urinary frequency, and a weak stream for 3 months. He has a medical history of obesity and hypertension. Family history is significant for prostate cancer in his father. Vital signs include: heart rate 76 beats/minute, blood pressure 150/90 mmHg, temperature 36.8°C (98.2°F), and respirations 14/minute. On physical examination, he has full range of the motion of the back and some tenderness to palpation over the lumbar spine. Digital rectal exam reveals a firm, nodular mass lesion. Prostate-specific antigen is 15 ng/mL. A bone scan demonstrates osteoblastic metastases in the lumbar spine.
Which of the following is the most likely diagnosis?
The correct answer is:
C) Prostate adenocarcinoma
Prostate cancer is the second most common cancer in men worldwide, with a median age of 66 years. Risk factors include age, male sex, African American ethnicity, family history, and obesity. Metastatic disease to bone is the most frequent site of distant spread for prostate cancer and is more common than metastases to organs like the liver (around 20-30%) or lungs (around 30-50%).
Answer choice B: Benign prostatic hyperplasia, is incorrect. Benign prostatic hyperplasia causes urinary symptoms in older men, but would not cause the back pain and bone scan findings seen in this patient. The elevated prostate-specific antigen >10 also suggests malignancy.
Answer choice C: Bladder transitional cell carcinoma, is incorrect. Bladder cancer typically presents with hematuria but would not demonstrate prostatic nodularity or bone metastasis, which is typical of prostate origin.
Answer choice D: Renal cell carcinoma, is incorrect. Renal cell carcinoma causes flank pain and hematuria, paraneoplastic syndromes, and venous invasion but not prostatic findings or prostate-specific antigen elevation.
Answer choice E: Testicular germ cell tumor, is incorrect. Testicular germ cell tumors tend to occur in younger men ages 20-40 years and present with a painless testicular mass along with elevated beta-HCG and alpha fetoprotein levels.
Key Learning Point
Prostate cancer risk rises with advancing age, male sex, family history, and obesity. PSA can be useful in symptomatic cases, with bone metastasis being common in more advanced disease.
