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 
It may be unilateral (76%) or bilateral (24%) . 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 .
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 .
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 .
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.
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