144: Cystic Diseases of the Kidney, Polycystic Kidney Disease

Key Points

• Disease summary:

  • Cystic diseases of the kidney are a heterogeneous group of hereditary, developmental, or acquired disorders that have in common the presence of renal cysts.

  • A renal cyst is a fluid-filled cavity lined by epithelial cells that derives primarily from the renal tubules, loosing its connection with their origin tubule once developed.

  • Polycystic kidney disease (PKD) is a group of monogenic disorders that result in renal cyst development, being autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) the most common forms.

  • ADPKD, caused by mutation in PKD1 or PKD2, is generally a late-onset multisystem disorder characterized predominantly by bilateral renal cysts and variable extra renal manifestations (extrarenal cysts, cardiac valvular defects, arterial aneurysms, colonic diverticulosis, abdominal wall hernias)

  • ARPKD, most commonly affecting newborns and young children, is caused by mutation in PKHD1 and is characterized by enlarged echogenic kidneys and congenital hepatic fibrosis.

• Hereditary basis:

  • ADPKD is the most frequent inherited renal disorder (1 in 400-1000) and follows an autosomal dominant inheritance pattern with complete penetrance and high intrafamilial variability.

  • ARPKD follows an autosomal recessive inheritance with an incidence of approximately 1:20.000; the frequency of heterozygosity is approximately 1:70.

• Differential diagnosis:

  • Cystic diseases in the differential diagnosis of ADPKD: ARPKD, other systemic diseases associated with renal cysts such as tuberous sclerosis complex (TSC), von Hippel-Lindau disease (VHL), and orofacial digital syndrome type 1 (OFDS), acquired renal cystic disease (ARCD) in patients with end-stage renal disease (ESRD), medullary sponge kidney, and simple cysts (Table 144-1).

  • Cystic diseases in the differential diagnosis of ARPKD: early-manifesting ADPKD, a group of inherited pleiotropic disorders causing polycystic kidneys (nephronophthisis [NPHP], Joubert syndrome and related disorders [JSRD], Meckel syndrome [MKS], Bardet-Biedl syndrome [BBS]), glomerulocystic kidney disease, and diffuse cystic dysplasia.