Adenocarcinoma of the colon and urinary bladder: A fortuitous or an embryological phenomenon?

Primary adenocarcinoma of the urinary bladder is a rare malignancy with a frequency of less than 2% of all urothelial malignancies. Colonic adenocarcinoma has a much higher prevalence and its infiltration/metastasis in the urinary bladder is a pertinent differential of primary adenocarcinoma of the urinary bladder. However, the distinction of infiltration by colonic adenocarcinoma from synchronous adenocarcinoma in the bladder and colon is not always easy. Here, we report a 42-year-old male, who initially presented with bladder symptoms and subsequently found to have growth in both bladder and colon. A diagnosis of adenocarcinoma was made from the biopsies from both bladder and colon. Further attempts to differentiate synchronous occurrence or secondary involvement from an adjacent organ was made by radiology, and by an immunohistochemistry panel. The loss of MLH1 and PMS2 coupled with histomorphology and radiology helped in the diagnosis of primary colonic adenocarcinoma infiltrating the urinary bladder.