Yoon H, Kim MJ, Shin HJ, et al. - Manifestations of localized cystic disease of the kidney (LCDK) can include millimetric calcifications (39%), contralateral millimetric renal cysts (11%), and mild size increment during renal growth (22%) in children without renal function impairment. These typical cases should undergo follow-up ultrasonography (US) without surgical intervention.

• A retrospective review of 18 pediatric patients (male:female = 11:7; median age, 8 years) diagnosed with LCDK based on imaging results demonstrating multiple localized renal cysts with intervening normal renal parenchyma from January 2002 to August 2020.

• Incidental findings (n = 5), abdominal pain (n = 5), or hematuria (n = 5) were initial clinical presentations of these cases.

• On US, multiple hyperechoic foci with ring-down artifacts within the cystic lesions were evident in seven patients (7/18, 39%), of these, six patients exhibited focal calcification of the cysts on CT.

• Presence of millimetric cysts in the contralateral kidney was identified in two patients (2/18, 11%).

• Follow-up (range, 2–122 months) revealed an increment in lesion size, with ipsilateral renal growth in 4 patients (4/18, 22%).

• In all cases, no renal function impairment was seen at initial presentation or during follow-up.