Primary bladder adenocarcinoma versus metastatic colorectal adenocarcinoma: a persisting diagnostic challenge

Aim: This study attempted to distinguish primary bladder adenocarcinoma (PBA) from metastatic colonic adenocarcinomas (MCA), which is a difficult diagnostic and clinical problem.Methods: Twenty-four cases of bladder adenocarcinomas (12 primary & 12 metastatic colorectal) were included in the study with urothelial carcinoma (UC) and colonic adenocarcinoma (CA) as controls. A panel of immunohistochemical (IHC) stains along with fluorescence in-situ hybridization (FISH), using the UroVysion probe set, was performed.Results: The majority of the PBAs presented with advanced disease. Enteric histologic subtype was the most common morphological variant. Strong nuclear with cytoplasmic-membranous staining of β-catenin was seen in 75% of MCA and only 16.7% PBA (