[Complicated urachal cyst: a difficult differential diagnosis].

Embryologically, the allantois connects the urogenital sinus with the navel. Normally, the allantois is oblitered before the birth and is represented by a fibrous cord, called urachus, extending from the dome of the bladder to the navel. Urachal formation is directly related to bladder descent. Incomplete obliteration sometimes occurs. Disease rarely occurs in urachus, but adenocarcinoma is the most fearful and rare, and it represents the 0.01% of the whole adult carcinoma, the 0.17-0.34% of the whole bladder malignancy, and the 20-30% of the bladder adenocarcinoma. Yet urachus may be seat of other kinds of benign pathologies characterized by incomplete obliteration of its lumen. Only if the ends of the urachus seal off, a cyst of that body may form and may become quite large, presenting a low midline abdomen mass. Adenocarcinoma may occur in a urachal cyst, particularly at its vescical extremity. Cystis usually have an asymtomatic course. Occasionally these cystis can be discovered during sonographic examination. If the cyst becomes infected, signs of general and local sepsis will develop, sometimes involving the peritoneum. Sometimes, in these cases, it is difficult to diagnose the presence of an adenocarcinoma and, particularly, its cystic variant. By using the common diagnostic instrumental device, we cannot reach a certain diagnosis, essential to perform a correct medical or surgical treatment. The case reported concerns a twenty-five years old man, over and over again examined, complaining of ipo-mesogastric abdominal pain, mild fever, increment of flogosis index and transaminasis, microscopic hematuria and urinal discomfort. Sonographic suprapubic examination, performed during urological consultation, showed an urachal neoplasm. Cystoscopy and TC evaluation didn't permit a certain preoperative diagnosis. A surgical explorative operation was performed and the neoplasm, a part of a bladder dome, omental flap and a part of rectus muscles, were removed. In order to reconstruct the abdominal wall we used a large Polypropilene patch. The hystological report outlined a large urachal cyst, a flogosis and a purulent necrosis invading the surrounding tissue and the peritoneum. The patient was discharged after twenty-five days and he had a good functional performance. In the light of the reported case, the surgical treatment seems to be the best solution before the onset of complications that should expose patients to difficult and demolitive surgical operations and that should protract the hospitalization.