Typical radiological findings in children with cystic kidney disease. (a, b) Typical ubiquitous macrocysts and enlarged kidney volumes are found a 15-year-old boy with ADPKD. (c) ARPKD typically presents with hyperechogenic kidney with microcysts as shown in a sonography of a 1-year-old boy. (d) The massively enlarged kidney volume in ARPKD is illustrated on axial abdominal MRI of a 10-month-old girl. (e) Ultrasonography of patients with nephronophthisis often shows small, hyperechogenic kidneys without corticomedullar differentiation. If present, cysts are typically found at the corticomedullar border. (f) Cerebellar vermis asplasia and elongated superior cerebellar peduncles result in the Molar Tooth Sign on axial MRI, which is pathognomonic for Joubert syndrome. ADPKD, autosomal dominant polycystic kidney disease; ARPKD, autosomal recessive polycystic kidney disease.