Brunn's Cyst Presenting with Lower Urinary Tract Symptoms: Role of Computed Tomography Intravenous Pyelography in Diagnosis

Brunn's cyst is an extremely rare benign intravesical lesion arising from cystic dilatation of von Brunn's epithelial nests and may present with lower urinary tract symptoms due to bladder outlet obstruction. We report a case of a 21-year-old male presenting with obstructive urinary symptoms in whom ultrasonography demonstrated a thin-walled anechoic cystic lesion at the bladder neck, raising suspicion of ureterocele. Computed tomography intravenous pyelography revealed a well-defined intravesical cystic lesion measuring approximately 1.9 × 1.6 cm, with a thin wall (∼1.4 mm) and homogeneous fluid attenuation (∼18 HU), without internal septations or postcontrast enhancement. There was no communication with the distal ureter and no associated hydroureteronephrosis. Cystoscopy demonstrated a smooth, dome-shaped cystic lesion at the bladder neck. Histopathological examination confirmed cystic dilatation of von Brunn's nests. This case highlights the importance of cross-sectional imaging in differentiating Brunn's cyst from other cystic lesions near the bladder neck.