[Urachal cyst: an unusual cause of intestinal obstruction].

Contribution of one case of urachal cyst in a patient initially diagnosed with intestinal obstruction due to a probable colon-sigma neoplasia. The patient underwent discharge colostomy after finding an extension of the likely tumour to abdominal wall, bladder and right ureter. Later, the patient was reassessed and the CT showed a mass in the bladder's anterior edge with disclosure of purulent material and inflammatory cytology through the PAAF. The treatment performed was partial cystectomy, closure of colostomy and rectum-sigma re-anastomosis. Histological diagnosis was urachal cyst, abscess and pyogenic membranes, with no evidence of tumoral tissue. The idiosyncrasy of this urachal cyst is the simulation of an intestinal obstructive process of tumoral origin. Differential diagnosis in these intestinal processes rarely includes urachal cyst.