Forniceal Rupture in Neonate Masquerading as a Cystic Renal Mass.

A 5-week-old full-term female with high-risk right hydronephrosis was transferred to the emergency department (ED) for tachypnea. A contrast-enhanced computed tomography (CT) study demonstrated a 9.0 cm cystic lesion in the region of the previously seen hydronephrosis (Fig. 1). Urology was consulted to rule out a cystic neoplasm, which on review of imaging was more suggestive of a contained forniceal rupture. An ultrasound-guided percutaneous nephrostomy tube drained 200 cc of urine. Culture and cytology were negative. Respiratory status markedly improved. The patient was discharged with outpatient follow to evaluate for ureteropelvic junction obstruction.