Dysplastic Kidney (MCDK) is an enlarged kidney whose parenchyma is replaced by multiple, non-communicating cysts, of variable size and number the incidence of MCDKD is about 1 in 5,000-10,000 births [1]
It may be unilateral (76%) or bilateral (24%) [2]. The recognition of bilateral MCDKD by ultrasound has important prognostic implication as it is a fatal anomaly.
Etiology: There are diverse etiologies of MCDK, they can be considered part of polymalformation syndromes, or may be secondary to chromosomal pathologies [3].
Pathogenesis: The possible embryologic causes are either an interference of nephron induction by the metanephric blastema, or a defect of communication between the ureteric bud and the metanephric blastema. A possible role of vascular compromise has also hypothesized.
Diagnosis and sonographic findings: The prenatal diagnosis can be made by ultrasound, allowing visualization of the both of kidney with multiple non-communicating cysts of variable size, mixed with hyperechogenic parenchyma, associated to severe oligohydramnios and the bladder cannot be visualized.
Differential diagnosis: Differential diagnoses include mesoblastic nephroma, wilms tumor, thrombosis of the renal vein, the renal cystic disease of obstructive renal dysplasia [4].
Associated anomalies: In case of dysplasia involving both kidneys, oligo/anhydramnios is usually associated, with consequent pulmonary hypoplasia and Potter sequence.
Prognosis: the prognosis is unfavorable due to the presence of the oligohydramnios, related to the complete renal insufficiency, which may result in the Potter sequence and death from lethal pulmonary hypoplasia [5].
Management: When the multicystic disease is bilateral, a conservative approach is recommended, after the 24th week, due to the unfavorable prognosis, mainly related to pulmonary hypoplasia.
References
1. Paladini D, Volpe P. Ultrasound of Congenital Fetal Anomalies. Informa Healthcare, 2007.
2. Lazebnik N, Bellinger MF, Fergusson JE, Hogge JS, Hogge WA. Insights into the pathogenesis and natural history of fetuses with multicystic dysplastic kidney disease. Prenat Diagn 1999; 19 : 418-23
3. Evans JA. Urinary tract. In: Stevenson RE, Hall JG. Human Malformations and Related Anomalies, second edition. Oxford. Oxford University Press. 2006: 1161-90.
4. Bianchi D, Crombleholme T, D' Alton M, Malone F. Fetology: Diagnosis and Management of the Fetal Patient. Second Edition. McGraw Hill Professional, 2010; 589-95.
5. Damen-Elias HA, De Jong TP, Stigter RH, Visser GH, Stoutenbeek PH.Congenital renal tract anomalies: outcome and follow-up of 402 cases detected antenatally between 1986 and 2001.Ultrasound Obstet Gynecol. 2005 Feb;25(2):134-43.