Adult primary obstructive megaureter revealed by a 2-cm ureterovesical junction stone.

Primary obstructive megaureter (POM) is an uncommon congenital anomaly rarely diagnosed in adults. We report the case of a 20-year-old man presenting with intermittent left flank pain for six months. Computed tomography revealed a markedly dilated left ureter containing a giant ureteral stone. The patient underwent open ureteral reimplantation with successful removal of the ureteral calculus. Postoperative recovery was uneventful, and renal function was preserved. This case highlights the importance of considering Primary obstructive megaureter in the differential diagnosis of adults presenting with hydronephrosis and urolithiasis, as early recognition and appropriate surgical management can prevent renal impairment.