AbstractBackgroundWe analyzed the clinical data of patients with urachal carcinoma (UrC) in order to strengthen urologists' understanding of UrC and improve preoperative diagnosis.MethodsThe clinical data of 37 patients with UrC admitted to our hospital from October 2005 to April 2022 were retrospectively analyzed, and 40 patients with urothelial carcinoma (UCa) of bladder were enrolled as the control group. We compared and analyzed the imaging, cystoscopy and immunohistochemistry, serum tumor markers, fluorescence in situ hybridization (FISH) of UrC and bladder UCa for early diagnosis and evaluation of diagnostic accuracy.ResultsA total of 37 patients with UrC were enrolled in this study, including 30 males and seven females, with a median age of 52.00 (44.50–63.50) years. Imaging and cystoscopy suggest that UrC grows primarily outside the bladder cavity and is found in the middle line of the dome or anterior wall of the bladder. There was a significant difference in tumor location between the UrC group and the UCa group (10.13 mm vs. −7.06 mm,p< 0.001). Immunohistochemistry revealed that CK20 and CDX‐2 were both diffusely and strongly positive. β‐catenin was strongly positive in cytoplasm and membrane, but negative in nuclear staining. Carcinoembryonic antigen (CEA) and carbohydrate antigen 72‐4 (CA724) expression levels were significantly higher in the UrC group than in the UCa group (p< 0.05). In the diagnosis of UrC, the area under the curve (AUC) of CEA combined with CA724 was the greatest. FISH's sensitivity in diagnosing UrC (5/7, 71.43%) was not significantly different from that of UCa (71.43% vs. 77.50%,p= 0.659). Imaging examination has the highest sensitivity and specificity among the accuracy evaluation of different diagnostic methods.ConclusionsImaging and cystoscopy are the powerful diagnostic methods for UrC. Serum tumor markers may assist in diagnosis, prognosis, and monitoring. Positive urine FISH can easily misdiagnose UrC as UCa