Medullary cystic disease complex

Medullary cystic disease complex belongs to group of paediatric cystic renal diseases charaterised by progressive tubular atrophy with glomerulosclerosis (chronic tubulointerstitial nephritis) and multiple small medullary cysts. 

Epidemiology

There is no recognised gender predilection

Clinical presentation

Presentation with polydipsia and polyuria, due to initial tubular injury, tends to progress to end stage renal failure, growth retardation, lethargy.

Three clinical variants based on age of onset for end stage renal disease (ESRD): 

• infantile: before 2 years of age
• juvenile (a.k.a. nephronophthisis): most common form, age of onset 10
• adolescent (a.k.a. medullary cystic kidney disease): usually develops in patients in their thirties

There can be a clinical triad comprising of uraemia, anaemia, and salt wasting (hyponatremia, hypokalemia).

Pathology

It comprises a group of related conditions characterised by multiple cysts typically at the corticomedullary junction and medulla. The medullary cysts are small. There can be associated atrophy and fibrosis of the basement membrane of the proximal and distal tubules which leads into interstitial fibrosis and end stage renal disease.

Variants

• familial nephronophthisis: autosomal recessive (40%)
• sporadic: non-familial (20%)
• retinal renal syndrome: autosomal recessive (15%) associated with retinitis pigmentosa
• adult onset medullary cystic disease: autosomal dominant (15%) 

Radiographic features

Normal to small kidneys with multiple small (<1.5 cm) medullary cysts (sometimes cysts are too small to visualise) at the corticomedullary junction.