Case Report: We report about a 35 year old male who was diagnosed with the rare villous adenoma of the urachus after presenting with macroscopic haematuria and undergoing transurethral resection of bladder tumour (TURBT) at another institution. Urachal Adenocarcinomas are rare aggressive cancers of the bladder and account for less than 1% of all bladder malignancies. Subsequent TURBT in 2016 revealed no change in his histology; however, the patient failed to attend follow‐up arrangements until he presented with clot retention in 2018. Computed tomography demonstrated an urachal mass and on this occasion histology revealed adenocarcinoma of the bladder. He underwent a partial cystectomy and bilateral extended pelvic lymph node dissection. Histopathology revealed adenocarcinoma of enteric type with metastatic carcinoma present in left pelvic and common iliac lymph node groups. The patient is currently receiving adjuvant chemotherapy.

Discussion: For primary urachal adenocarcinomas, the mean 5‐year overall survival is poor at 43%. The traditional TNM staging criteria used for bladder cancers does not apply as urachal tumours arise outside the bladder and grow secondarily into the bladder. In some cases, these cancers do not invade into the bladder. The two main staging criteria are the Sheldon and Mayo staging systems.

The MD Anderson Cancer Centre diagnostic criteria can help with diagnosis of urachal carcinoma.

The two criteria include:

1. location in the bladder dome or in the midline of the bladder;
2. sharp demarcation between tumour and normal surface epithelium.

Supportive criteria to assist include:

• Enteric‐type histology
• Absence of urothelial dysplasia
• Absence of cystitis cystica or cystitis glandularis transitioning to the tumour
• Absence of primary adenocarcinoma of another organ Standard surgical management for localised urachal carcinoma is partial cystectomy and excision of the urachus with bilateral extended pelvic lymph node dissection. There is currently no standardised adjuvant chemotherapy protocol; however, cisplatin based combination regimens are often used.