Urachal abnormalities: clinical and imaging features.

Introduction: The clinical manifestation of urachal abnormalities may mimic many intraabdominal or pelvic diseases. We present clinical, imaging and pathological findings of a spectrum of complicated urachal abnormalities and determine whether imaging can be used to differentiate tumour from infection.

Methods: From January 1993 to December 2006, seven patients with surgically-proven complicated urachal abnormalities had their clinical, imaging and pathological features reviewed.

Results: There were three men and four women, aged 12-73 years. Four patients had infected urachal remnants and three had urachal carcinoma. The main clinical findings in infected urachal remnants were dysuria, abdominal pain and mass. The patients of urachal carcinoma presented with abdominal mass and haematuria. Computed tomography (CT) was performed in all cases, and ultrasonography (US) was performed in four cases. CT in all cases showed a mass located extraperitoneally in the midline just beneath the rectus abdominis muscle and extending from the umbilicus to the dome of the urinary bladder. There were one well-defined cystic mass and six ill-defined solid masses. US showed one cystic mass and three echogenic masses. Cystography was performed in one patient and it showed indentation to the dome of the urinary bladder with mucosal irregularity. The cystic mass and one ill-defined solid mass were pathologically-proven to be xanthogranulomatous inflammation. The other five solid masses were found to be adenocarcinoma in three and chronic non-specific inflammation in two cases.

Conclusion: Preoperative diagnosis of urachal abnormalities may be suggested by clinical presentation and imaging features. However, it is difficult to differentiate tumour from infection based on imaging features alone.