Polycystic liver disease—Polycystic liver disease (PLD) is the most common extrarenal manifestation of ADPKD. Liver cysts originate from small clusters of intralobular bile ductules surrounded by fi brous tissue termed biliary microhamartomas and from peribiliary glands. The occurrence of PLD in ADPKD increases with age from 0% in ADPKD children to 20% in the third decade and over 75% in the seventh decade of life. Women, especially those with multiple pregnancies and/or on oral contraceptive or on estrogen replacement therapy, tend to have an earlier onset and worse PLD.
The majority of PLD patients are asymptomatic. When occurring, the symptoms usually result from either mass effect or cyst-related complications such as cyst hemorrhage, rupture, or infection. The liver synthetic functions are typically preserved because, despite even a signifi cant degree of cystic liver involvement, the total amount of unaffected hepatic parenchyma is not reduced. Symptoms associated with mass effect are dyspnea, orthopnea, early satiety, gastroesophageal refl ux, mechanical back pain, uterine prolapse, rib fracture, and, in severe cases, failure to thrive. In rare cases, a massively enlarged cystic liver can cause obstructions to the hepatic venous outfl ow tract, portal vein and/or bile duct, or the inferior vena cava. These patients may develop portal hypertension, esophageal and/or gastric varices, ascites, and, rarely, obstructive jaundice.
Hepatic cyst hemorrhage and ruptures can present as acute abdominal pain, extrinsic bile duct compression, and liver enzyme elevation. Rarely, cysts can rupture into the peritoneum and cause acute ascites and life-threatening hemoperitoneum.
Patients with hepatic cyst infection may present with fever, chills, localized upper abdominal pain, leukocytosis, and elevation of alkaline phosphatase. Bacteremia is frequently present. The major pathogens are Enterobacteriaceae.
Intracranial aneurysms and other vascular manifestations—The incidence of intracranial aneurysms (ICAs) and ICA ruptures in ADPKD is increased by 5- to 10-fold compared to that in the general population. Family clustering is evident. Patients with a family history of ICA or subarachnoid hemorrhage (SAH, the consequence of ICA rupture) have an ICA occurrence of 21% versus 6% in those without such history.
The majority of ADPKD-associated ICAs are small (<7 mm in diameter) and are located in the anterior circulation (approximately 90%). Although compared to sporadic ones, ICAs in ADPKD have a younger mean age of aneurysmal rupture (39 versus 51 years).
The risk of ICA rupture (extrapolated from the International Study of Unruptured Intracranial Aneurysms) depends on the size and location of the ICAs and whether the patient has a prior episode(s) of SAH.
The yearly risk of rupture is less then 0.1% for the small sized (<7 mm in diameter) anterior circulation ICAs in patients without a prior SAH. The risk is higher for ICAs >7 mm in diameter or in the posterior circulation or in patients with a prior history of SAH.
Unruptured ICAs are generally asymptomatic. Rarely, patients can present with focal neurologic symptoms such as cranial nerve palsy or seizure due to local compression. Rupturing or ruptured ICAs typically present with prominent symptoms including episodes of sudden onset intense headache or headache with a quality different from that experienced before. The pain can radiate to the occipital and cervical region and may be accompanied by nuchal rigidity. Other associated symptoms are nausea, vomiting, photophobia, cranial nerve palsy, seizure, lethargy, and coma.
Other vascular manifestations more frequently seen (an approximately 10-fold increase) in ADPKD are thoracic aortic and cervicocephalic arterial dissections, intracranial arterial dolichoectasia, and coronary artery aneurysms. The symptoms and signs of these complications are similar to those seen in non-ADPKD patients.
Valvular heart disease—Valvular heart diseases occur more frequently in ADPKD patients than in their nonaffected family members or the general population. Of those, mitral valve prolapse is the most common and can be detected by echocardiography in up to 20% of ADPKD patients.
Other more frequent valvular heart diseases include mitral insufficiency, tricuspid insufficiency, tricuspid prolapse, and aortic insufficiency often associated with aortic root dilation. Symptoms vary from asymptomatic or episodic palpitations to, in rare cases, congestive heart failure. When a cardiac murmur is heard, antibiotic prophylaxis against subacute bacterial endocarditis is indicated.
Renal cell carcinoma—Despite the frequent occurrence of hyperplasia and microscopic adenomas on renal pathology, the overall incidence of renal carcinoma in ADPKD is not increased.
However, when occurring, the renal cancer tends to affect younger patients (mean age of 45 versus 55 years in the general population), be multifocal, and possess high-grade sarcomatoid features.
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