Primary enteric-type adenocarcinoma of the urinary bladder is relatively uncommon. We present our experience with 109 pure, non-urachal cases—the largest series to date. This work was undertaken with the aim of describing the immunohistochemical features of adenocarcinoma of the urinary bladder associated with schistosomiasis, illustrating their histologic and immunohistochemical similarities to colorectal carcinomas. Partial or total cystectomy specimens from a cohort of Egyptian and American patients with the diagnosis of primary adenocarcinoma of the urinary bladder (109 cases) were reviewed. Paraffin sections of each tumour were stained using the labelled streptavidin–biotin method using antibodies cytokeratin 20, cytokeratin 7, CDX2, MLH1, and villin. Clinical follow-up was available for at least 36 months. An enteric (colonic) morphology was seen in most tumours; some with signet ring cells or mucinous elements. Five tumours were composed predominantly of signet ring cells and two demonstrated a pure mucinous morphology. In cases where adjacent normal mucosa was present, 23% showed either colonic metaplasia or intestinal-type cystitis glandularis. Furthermore, 24% of enteric-type adenocarcinomas had associated villous or tubulovillous adenomas with or without dysplasia. Cytokeratin 20 was expressed by 90%, cytokeratin 7 by 17%, CDX2 by 100% and villin and MLH1 by 76% and 48% of tumours respectively. The majority of tumours presented with an advanced stage and followed an aggressive clinical course. | Primary enteric-type adenocarcinomas of the urinary bladder are histogenetically analogous to colorectal carcinomas: Immunohistochemical evaluation of 109 cases
