Diagnosis and long-term outcome of renal cysts after laparoscopic partial nephrectomy in children

Objective To document the imaging follow-up of laparoscopic partial nephrectomy (LPN) in children and to investigate the natural history of cystic lesions following LPN. Patients and Methods We reviewed the ultrasonography (US) imaging reports performed during the follow-up of 125 children (77 girls, 48 boys; mean age 3.2 years) who underwent LPN in two centres of paediatric surgery in the period 2005-2015. Results A transperitoneal approach was adopted in 83 children and a retroperitoneal approach in 42. The mean follow-up was 4.2 years. At US, an avascular cyst related to the operative site was found after 61/125 procedures (48.8%). As for their appearance, 53/61 cysts were simple and anechoic, and eight of the 61 cysts appeared septated. The mean diameter of the cysts was 3.3 9 2.8 cm. As for their course, 13/61 cysts (21.3%) disappeared after a mean of 4 years, 26/61 (42.6%) did not significantly change in dimension, 17/61 (27.8%) decreased in size, and only five of the 61 cysts (8.3%) enlarged. The cysts were asymptomatic in 51 children (83.6%), while they were associated with urinary tract infections (UTIs) and abdominal pain in the remaining 10; none required a re-intervention. Conclusions The US finding of a simple cyst at the operative site after LPN is common during follow-up, with an incidence of similar to 50% in our series. In regard to aetiology, probably a seroma takes the place of the removed hemi-kidney. There was no correlation between cyst formation and type of surgical technique adopted. As there was no correlation between cysts and clinical outcomes, renal cysts after LPN can be managed conservatively, with periodic US evaluations.