Imaging-negative renal hydatid disease diagnosed intraoperatively during nephron-sparing surgery.

Hydatid disease uncommonly involves the kidney and is particularly rare in children. We report a paediatric case of isolated renal hydatid cyst that radiologically appeared as a Bosniak II simple cortical cyst without classical signs such as daughter cysts, calcification or membrane detachment. Preoperative diagnosis favoured a benign renal cyst and serology was unavailable, resulting in hydatid disease being identified intraoperatively following cyst aspiration and visualisation of membranes. Nephron-sparing cystectomy was performed using controlled anti-spillage technique with povidone-iodine irrigation and perioperative albendazole therapy. Histopathology confirmed echinococcal infection. This case highlights the diagnostic challenge of imaging-negative renal hydatid disease and demonstrates the feasibility of nephron-sparing surgery in children. Isolated renal hydatid disease may mimic benign cystic lesions in paediatric practice and require intraoperative recognition to avoid complications and preserve renal function.