Adult Polycystic Kidney Disease

Case History: A 78-year-old patient presented with history of hypertension and renal failure.

Figures 1 -4 show both kidneys with multiple cysts.

Ultrasound findings: Both the kidneys are enlarged in size. Both kidneys show multiple cysts. Few of the cysts in both kidneys show calcification at their periphery. Overall echogenicity of both kidneys is little increased. No cyst seen in liver and pancreas.

Diagnosis: Autosomal dominant polycystic kidney

Discussion: Polycystic kidney disease (PKD or PCKD, also known as polycystic kidney syndrome) is a cystic genetic disorder of the kidneys. There are two types of PKD: autosomal dominant polycystic kidney disease (ADPKD) and the less-common autosomal recessive polycystic kidney disease (ARPKD).

It occurs in humans and some other animals. PKD is characterized by the presence of multiple cysts typically in both kidneys; however 17 percent of cases initially present with observable disease in one kidney, with most cases progressing to bilateral disease in adulthood. The cysts are numerous and are fluid-filled, resulting in massive enlargement of the kidneys. The disease can also damage the liver, pancreas and, in some rare cases, the heart and brain. The two major forms of polycystic kidney disease are distinguished by their patterns of inheritance.

Polycystic kidney disease is one of the most common life-threatening genetic diseases, affecting an estimated 12.5 million people worldwide. Adult polycystic kidney disease, which affects approximately 1 in 1000 people, is transmitted as an autosomal dominant trait. Cysts arise from the nephrons and collecting tubules; microdissection reveals that the cysts communicate directly with the nephrons and collecting tubules. Islands of normal parenchymal renal tissue are interspaced between the cysts.

Patients present with hypertension and progressive renal failure after their third decade of life. Autosomal dominant polycystic kidney disease (ADPKD) is uncommon in children and is rarely seen in neonates.

Ultrasonography is the procedure of choice in the workup of patients with ADPKD, and it is an ideal modality for screening patients' families. Computed tomography (CT) scanning is as sensitive as ultrasonography in the detection of cystic disease, although problems may arise with smaller cysts. CT scanning appears to be more specific than ultrasonography in differentiating an obstructed renal pelvis from a parapelvic cyst. It also seems to be superior to ultrasonographic images in helping to assess retroperitoneal rupture of a cyst and perinephric extension of blood or pus from an infected cyst.

Magnetic resonance imaging (MRI) is especially useful for examining patients who are allergic to iodinated contrast media and those with compromised renal function who are at risk for iodinated contrast–induced renal failure. MRI also has advantages for patients in whom hemorrhagic cysts are considered and is probably superior to other modalities in characterizing complicated cysts.

Radionuclide studies have a complementary role in the assessment of renal function in ADPKD. These studies do not have the added hazard of patient exposure to iodinated contrast material.

 Harpreet Singh, MD
JP Scan private diagnostic center, Khanna, Punjab, India