Incidentally found abdominal para-aortic and inferior mesenteric root lymph node metastases of prostatic adenocarcinoma in a surgical case with sigmoid colon cancer

We report a rare case of incidentally found metastatic adenocarcinoma in the abdominal para-aortic and inferior mesenteric root lymph nodes originating from the prostate, at the time of surgery in a patient with sigmoid colon cancer. A man in his mid-seventies was scheduled to undergo laparoscopic-assisted sigmoidectomy and regional lymph node dissection. At the beginning of laparoscopic surgery, a caterpillar-like swelling of abdominal para-aortic lymph nodes was found; the diagnosis using frozen sections was a metastatic adenocarcinoma showing cribriform and solid growth patterns different from typical colorectal cancer. The surgical procedure was changed to an abdominal sigmoidectomy with widely extended lymph node dissection, including inferior mesenteric root lymph nodes and sampling of abdominal para-aortic lymph nodes. The resected sigmoid colon cancer was a papillary/tubular adenocarcinoma invading the muscularis with no lymph node metastasis (pT2N0M0/pStage IIA). Additionally, the presence of a metastatic adenocarcinoma showing cribriform and solid growth patterns different from the primary sigmoid colon cancer was confirmed in the abdominal para-aortic and inferior mesenteric root lymph nodes. The metastatic adenocarcinoma cells were positive for prostate-specific antigen (PSA) and negative for CDX2, indicating that the tumor was from the prostate. A total of ten prostatic core needle biopsy specimens also contained a usual (acinar) adenocarcinoma, with a Gleason score of 4 + 5 = 9. Androgen blockade was performed; the serum PSA level was reduced to 0.06 nanograms per microliter in the subsequent five months. Regardless of radiologic images, examination of serum PSA level is recommended before surgery in male surgical colorectal cancer patients more than 60 years old.