Renal Cyst Disorders

Snapshot

• A 26-year-old man presents to his primary care physician with abdominal and lower back pain. He reports to also seeing blood in his urine. Medical history is non-contributory. Family history is significant for his father requiring hemodialysis at a young age. Vitals signs are significant for a blood pressure of 162/112 mmHg. A renal ultrasound is performed and shown. (Adult polycystic kidney disease)

Adult Polycystic Kidney Disease (ADPCKD)

• Clinical definition
  • an inherited disorder that results in expansion of multiple renal cysts which ultimately leads to end-stage renal disease
• Epidemiology
  • incidence
    • the most common inherited cause of kidney disease
  • demographics
    • ≥ 30 years of age
  • risk factors
    • family history
• Pathogenesis
  • PKD1 or PKD2 mutations results in abnormal cell signaling that results in cystogenesis
    • expansion of cysts results in progressive loss of nephrons
• Genetics
  • inheritance pattern
    • autosomal dominant
  • mutations
    • PKD1 (on chromosome 16) or PKD2 (on chromosome 4)  
      • PKD1 encodes polycystin-1 
      • PKD2 encodes polycystin-2
• Associated conditions
  • cyst development in other organs such as
    • liver (most common extra-renal cyst type)
    • pancreas
    • seminal vesicle
    • note, that kidneys appear normal at birth 
  • vascular abnormalities such as
    • intracranial aneurysm 
    • coronary artery aneurysm
  • cardiovascular abnormalities
    • mitral valve prolapse
    • left ventricular hypertrophy
  • diverticulosis
• Prognosis
  • with age the number and size of the cyst increases
• Presentation
  • symptoms
    • abdominal or flank pain
    • low back pain
    • hematuria
    • recurrent urinary tract infections
• hypertension

Juvenile Polycystic Kidney Disease (ARPCKD)

• Clinical definition
  • a congenital fibrocystic disorder that results in renal and hepatic manifestations
• Epidemiology
  • incidence
    • 1 in 20,000 live births
• Pathogenesis
  • PKHD1 gene mutation leads to abnormal production of fibrocystin and polyductin which results in defects of the
    • renal tubular structures
      • dilatation and elongation of collecting ducts
    • bile duct structures
      • cystic dilatation of intra- and extra-hepatic bile ducts
• Genetics
  • inheritance pattern
    • autosomal recessive
  • mutation
    • PKHD1 gene on chromosome 6 
• Associated conditions
  • Potter sequence 
• Presentation
  • symptoms/physical exam
    • bilateral abdominal mass in infants and children
    • hepatomegaly in infants and children
• hypertension

Medullary Cystic Disease

• Clinical definition
  • an autosomal dominant inherited disorder that results in tubulointerstitial fibrosis of the kidney 
  • medullary cystic disease is characterized by
    • autosomal dominant inheritance pattern
    • progressive and slow impairment in renal function that ultimately results in end-stage renal disease
    • no or minimal proteinuria with a bland urine sediment
    • medullary cysts on renal ultrasound
      • in most cases medullary cysts are not present
      • can see shrunken kidneys on ultrasound