Metastatic Adenocarcinoma of the Prostate Masquerading as a Splenic Flexure Colonic Polyp: A Diagnostic Conundrum

Metastasis of prostate cancer to the gastrointestinal tract is infrequently described in the literature, with only a limited number of cases reporting metastasis to the rectum. We present a rare case of a 74-year-old man initially presenting with symptomatic anemia and weight loss. A colonoscopy revealed a sessile polyp in the splenic flexure. Microscopic examination of the specimen showed micro-acinar structures, and immunohistochemical staining was positive for prostate-specific antigen (PSA) and NKX3.1. Subsequently, elevated serum PSA levels and staging computed tomography (CT) findings, in conjunction with histopathological analysis, confirmed a diagnosis of metastatic prostate adenocarcinoma.