Case Report: Urachal calculus with an atypical intravesical CT appearance and literature review.

BACKGROUND: Urachal calculi are uncommon complications of urachal remnants. Their clinical and radiological appearances overlap with bladder calculi, vesicourachal diverticula, infected urachal cysts, and calcified urachal tumors, creating a potential diagnostic pitfall. CASE DESCRIPTION: A 54-year-old man presented with intermittent lower abdominal pain lasting more than six months without hematuria, dysuria, umbilical discharge, fever, or other lower urinary tract symptoms. Cystoscopy at a local hospital showed bladder inflammation but no stone. In our hospital, computed tomography demonstrated a 1.2 x 0.9 cm densely calcified lesion (approximately 1112 HU) at the junction of the bladder dome and anterior wall. The lesion appeared to lie within the bladder outline and initially mimicked a bladder diverticular calculus. Repeat cystoscopy at our institution identified a partially intravesical calculus with a component embedded in the urachal tract. The intravesical component was fragmented using a holmium laser, followed by laparoscopic partial cystectomy and en bloc excision of the urachal remnant and residual calculus. Histopathological examination showed an inflamed urachal remnant without intestinal metaplasia, dysplasia, or malignancy. The urinary catheter was removed after 2 days, and the patient was discharged after a 7-day hospitalization. Post-discharge recurrence could not be assessed because the patient was lost to follow-up. CONCLUSION: A midline calcification at the bladder dome should prompt consideration of a urachal origin even when it appears intravesical. Multiplanar CT assessment, systematic inspection of the bladder dome, and histological evaluation of the excised remnant are important for diagnosis and management.