[Megacalycosis in childhood].

Congenital megacalycosis is a renal dysplasia characterised by hypoplasia of the medullary pyramids and associated non-obstructive dilatation of the calyces. Calyceal dilatation promotes via disturbed urodynamics the manifestation of chronic interstitial nephritis and calculus formation. Therapy is primarily not necessary, but in the presence of stone development and chronic infections surgical procedures may become indispensable. Pathogenesis, diagnosis, differential diagnosis and therapy of megacalycosis in two children are discussed.