An elusive tumor in a man who has evidence of prostate cancer metastasis.

CASE A 65-year-old man presented for consultation because his prostate-specific antigen (PSA) level was elevated. The patient’s medical history is significant for a radical retropubic prostatectomy 11 years ago. Before the surgery, the patient’s serum PSA level was 3.0 ng/mL. Adenocarcinoma of the prostate was diagnosed by biopsy. The pelvic lymph nodes were negative at the time of the surgery; therefore, the disease was determined to be confined to the prostate. Pathology confirmed stage II adenocarcinoma with a Gleason score of 3+3. The patient’s serum PSA was subsequently undetectable; he was lost to follow-up for several years. When the patient returned in 2002, his PSA level was 0.2 ng/mL. The following year, it had increased to 0.3 ng/mL, and in 2005, it was 1.9 ng/mL. One month before this consultation, the patient’s PSA level was 9.4 ng/mL. At this visit, the PSA level was 10.56 ng/mL. The patient had no symptoms other than erectile dysfunction, a common side effect of prostatectomy. He had no new areas of bone pain and no new respiratory, GI, genitourinary, or neurologic complaints. CT with contrast of the pelvis and abdomen showed no obvious evidence of metastatic disease. A whole-body bone scan displayed some osteoarthritic changes but no definitive evidence of metastasis. Immunoscintigraphy with capromab pendetide (ProstaScint), a murine monoclonal antibody that reacts with prostate-specific membrane antigen (PSMA), was ordered. A low level of reactivity was seen in the prostatic fossa, but it was less intense than would be seen in recurrent disease. No reactive adenopathy or evidence of bony metastatic disease was apparent. However, focal radiotracer reactivity appeared in the upper lobe of the left lung (Figure 1). Chest CT revealed a spiculated lesion measuring 2.8 cm in diameter. The nodular density resembled a primary lung carcinoma; however, the lesion’s location correlated with the area of reactivity seen on the scintigram (Figure 2). Biopsy confirmed that the tumor was a prostate cancer metastasis, which was surgically removed in October 2006. The margins of the excision were negative, but vascular channel invasion by carcinoma existed. Treatment with leuprolide (Lupron) injections for systemic metastasis of prostate cancer was initiated. One month after resection of the lung tumor, the patient’s PSA level was 2.06 ng/mL, and it continued to decrease. Follow-up serum PSA levels were 0.07 ng/mL in March 2007 and 0.16 ng/mL in June 2007. At this time, the patient chose to proceed with pulse hormonal therapy. In September 2007, the patient’s PSA level had increased to 2.19 ng/mL. He continued to experience erectile dysfunction and noted having hot flashes, both of which were attributed to the hormone treatment. He had no other symptoms of metastatic disease.