Retroperitoneal Pseudoaneurysm Mimicking Ureteral Calculus: Pitfalls in Diagnosis

Arterial aneurysms (AA) can be classified as true aneurysms, characterized by the persistence of all three layers of the arterial wall with progressive dilation and wall thinning; arterial pseudoaneurysms (APAs) are characterized by a tear in the vessel wall and a periarterial hematoma formation. They could occur due to a visceral, retroperitoneal, or peripheral origin. Most AA/APA are usually found incidentally, and it is imperative to be vigilant in order to diagnose and manage them due to their potentially life-threatening complications. We present a case of a 35-year-old woman presenting with right-sided abdominal pain mimicking renal colic with an initial misdiagnosis of ureteral calculus. Post-cystoscopy, a misdiagnosis was confirmed, and subsequently, the patient had a right retroperitoneal mass excision. The histopathology report concluded the calcified retroperitoneal mass to be pseudoaneurysm. Such pitfalls in diagnosis are essential to be shared with the larger medical community for increased vigilance and optimal management of pseudoaneurysms.