Case of the Month: April, 2011 Page 4

Answer:  D: autosomal dominant polycystic kidney disease.

Discussion Points:

• This case is a rare presentation of unilateral ADPCKD as it most often affects bilateral kidneys.
  
• Epidemiology: Incidence 1:400-1,000. Three types based on gene location. Affects Males = Females. Found anywhere from childhood to 8th decade.
  
• Pathogenesis: Abnormal gene responsible for proliferation of renal tubular cells.
  
• Often asymptomatic, but may present with flank pain, hematuria, hypertension, and renal failure.
  
• Associated abnormalities: Cysts- Hepatic 75%, pancreatic 10%, splenic, and ovarian/testicular. Intracranial aneurysms 5-10% and cardiac valve defects 26%. Congenital hepatic fibrosis and biliary hamartomas.
  
• Imaging characteristics: enlarged kidneys with bilateral numerous cysts that are variable in size, round, have thin imperceptible walls +/- calcifications and do not enhance. Often hypodense but may be hyperdense if hemorrhagic.
  
• Differentiated by recessive form by ARPCKD having earlier onset and worse prognosis and cysts appear smaller.
  
• Complications: hemorrhage, infection, rupture, renal failure (4th leading cause), malignancy (rare).
  
• Treat symptoms and complications, ultimately treated with transplant.
  

References:

• www.statdx.com
• Wittenburg, et al. Primer of Diagnostic Radiology, 3rd ed. 2003.
• Middleton, et al. Ultrasound: The Requisites, 2nd ed. 2003.
• Webb, et al. Fundamentals of Body CT, 3rd ed. 2005