Older Male with a Large Rectal Mass

Rectum

52 year old male with a large rectal mass. Colonoscopy is performed and multiple biopsies obtained.

Multiple fragments of colorectal mucosa with a poorly differentiated infiltrating tumor. The tumor cells are in nests with prominent nucleoli and increased mitoses.

Immunohistochemical Stains Performed:

• CK 7 - negative
• CK20 - negative
• Pancytokeratin - positive
• P53 - positive
• Ki-67 - moderate activity
• PSA- positive

Not applicable for this case, please continue to the Diagnosis.

Adenocarcinoma of Prostate with Extension into the Rectum

Rectal involvement from prostate cancer occurs in 1.5-11% of cases. Direct extension to the bladder and invasion of the seminal vesicles can also be noted. This presentation of prostate cancer may be difficult to distinguish from primary colorectal cancer. Additional studies include: intravenous urography, radionuclide bone scan, acid phosphatase and or alkaline phosphatase.

1. Culkin DJ, Demos TC, Separate annular strictures of the rectosigmoid colon secondary to unsuspected prostate cancer, J. Surg Oncol. 1990. Mar; 43 (3) 189-92.