The most common form of congenital cystic abnormality is cystic dysplasia. This describes kidneys which have developed abnormally, the dysplastic renal parenchyma containing cysts.
Multicystic dysplastic kidneys (total renal dysplasia)
Cystic dysplasia with urinary tract obstruction (obstructive renal dysplasia)
Segmental dysplasia (with ectopic ureterocoele)
Diffuse cystic dysplasia (syndromal and non-syndromal)
Multicystic dysplastic kidneys (MCDK)
Multicystic dysplastic kidneys contain multiple cysts of varying sizes with no
identifiable pelvicalyceal system. The ureter draining the MCDK is atretic
and the kidney itself is non-functioning.
There is an association with abnormalities of the contra-lateral kidney, in particular vesico-ureteric reflux.
Obstructive renal dysplasia
Any form of congenital renal obstruction can produce dysplastic renal tissue.
This includes neuropathic bladder, posterior urethral valves, pelvi-ureteric
junction obstruction.
Diffuse cystic dysplasia
Diffuse cystic dysplasia results in enlarged, spongy kidneys with poor medullary
development. It typically occurs in association with
certain syndromes.