The answer to the image quiz from March 11, 2012 is ADPKD. The image shows enlarged kidneys with multiple cysts in an unenhanced axial computed tomography (CT) scan. The cysts are fairly well-defined, round or oval masses with low attenuation values similar to those of water.
The Question: What is the diagnosis on the CT image below?
10 Quick Facts on ADPKD
1. Autosomal
dominant polycystic kidney disease (ADPKD) is the most common of all
the hereditary cystic kidney diseases.
2. Incidence of 1 to 2:1,000 live births.
3. Accounts for 10% of ESRD patients in Europe and the U.S.
4. Characterized by progressive cyst development and
bilaterally enlarged kidneys with multiple cysts.
5. Three genetic
mutations in the PKD-1,
PKD-2, and PKD-3 gene with similar
phenotypical presentations.
- Gene PKD-1 is located on chromosome 16 and codes for a protein involved in regulation of cell cycle and intracellular calcium transport in epithelial cells, and is responsible for 85% of the cases of ADPKD.
- A group of voltage-linked calcium channels are coded for by PKD-2 on chromosome 4.
- PKD3 recently appeared in research papers as a postulated 3rd gene. At this time, PKD3 has not been proven.
6. Fewer than 10% of cases of ADPKD appear in non-ADPKD
families.
7. Patients present with hypertension
and progressive renal failure
after their third decade of life.
8. Between 29% and 73% of patients with the disorder have
associated hepatic cysts, 9% have associated pancreatic cysts, and 5% have
associated splenic cysts; pulmonary cysts occur but are uncommon.
9. Gardner and Evan showed that individuals older than age
40 years with a family history of ADPKD but without renal cysts are unlikely to
develop the disease. Others have shown that when screening for evidence of
ADPKD, if the kidney shows no signs of cysts or parenchymal abnormality in a
patient by age 19 years, that individual is extremely unlikely to be affected.
10. Ultrasonography is the procedure of choice in the workup
of patients with ADPKD, and it is an ideal modality for screening patients'
families (see the images below). Plain radiographs offer limited information.
- Ravine criteria (Lancet 1994;343(8901):824-827):
- diagnosis of ADPKD
- if there is a positive family history
- two renal cysts either unilateral or bilateral in patients under the age of thirty.
- In patients between the ages of 30 and 59, a minimum of two cysts must be present in each kidney.
- In patients over the age of 60, four cysts in each kidney is necessary for diagnosis.
- The use of these criteria reduces the false negative rate of diagnosis to less than 5%.
(Source: Wikipedia and emedicine)
