(http://www.cx.unibe.ch/ikp/lab2/PKD.html)
J. Reichen M.D.
The genes for ADPKD have been identified. PKD1 is localized on chromosome 16 and encodes a protein involved in protein-protein and protein-matrix interaction (1). The gene product, polycystin, is expressed in the plasma membrane in particular in renal tubular, pancreatic and bile duct epithelium but also in skin (2). The other gene, PKD2 has some similarities with PKD1 and is located on chromosome 4 (3). There appears to be a third gene with milder manifestations (4). PKD1 and PKD2 interact, PKD 1 requiring PKD2 for stable expression (5).
Polycystic liver disease is part of the ductal plate malformations (6,7); therefore there is sometimes overlap with congenital hepatic fibrosis and Caroli's disease (8). Polycystic liver disease can be associated with PKD1 (9) and PKD2; recently, a family with isolated liver cysts not associated with neither has been described (10). Finally, hepatic cysts can be associated with the Peutz-Jeghers syndrome (11).
The hepatic cysts are derived from biliary epithelium (12) and therefore responsive to secretin (13); they arise from biliary microhamartomas (von Meyenberg plexus) and initially may have communications with the biliary tree (14).
Cysts are more prominent in females than in males and increase with age usually up to the menopause (15). Postmenopausal estrogen induces cyst growth (16). Hepatic cyst size are larger in ADPKD and are correlated to severity of renal disease (17). In ADPKD even in the absence of liver cysts there is frequently bile duct dilatation (~40 %) presumably as an expression of the deficiency in cell-matrix interaction (18,19). Liver cysts are present in 25 - 35 % of patients with ADPKD (20,21). Arachnoid and other intracranial cysts are frequently found in ADPKD but require no treatment (22). In contrast, there is an association with intracranial aneurysms in about 4 % of patients (64). Because of the morbidity of angiography, high resolution CT or MR should be used as screening test (64).ComplicationsSevere complications are rare but patients, in particular women, have frequently marked symptoms, mostly pain and more or less pronounced symptoms of gastric outlet obstruction (23).
oPortal hypertension with varices (24)and variceal bleeding (25,26). This has been successfully treated in the past with portacaval shunting (27) and TIPS (28). oCalcifications (29) oObstructive jaundice (30,31). This complication is rare but in post-mortem specimens there are frequently changes of the bile ducts similar to those found in sclerosing cholangitis (32). Cholelithiasis may be increased. oInfection: Occurs in less than 1 % of patients without renal failure; once renal failure increases, up to 3 % develop infections (33,34). Described germs include S. aureus (34), E. Coli (34) Pseudomonas (35) and Salmonella (36) . A rare but feared infectious complications is liver abscess (37). oAscites which can be refractory to diuretic treatment (38). Ascites can be due to portal hypertension or to hepatic venous outflow obstruction (39). oVenous outflow obstruction involving the hepatic veins and/or the inferior vena cava (39, 40). oBleeding (41) and rupture. oNeoplasms, among others pancreatic cystadenocarcinoma (42) and adenoma of the ampulla (43).
In most patients, no treatment is necessary. Treatment is indicated when complications arise or when quality of life is severely impaired. In the opinion of this author, resection/defenestration is the best option. In selected cases liver or combined liver/kidney transplantation may be indicated. The following options have been described in the literature:
oRadiologic-interventional with cyst evacuation and alcohol instillation (44-46). Tetracyclines have also been employed (47-49). Drainage alone is not indicated since the cysts refill immediately (50); it has been used successfully for infected cysts, however (34). I have seen several infected cysts, however. This complication is rarely described by radiologists (48) but may be assumed to occur more frequently than conceded. oSurgical unroofing (50-52). This can be complicated by massive ascites, however (52). Recurrence of hepatomegaly in about 15 % (52). Unroofing should not be associated with Roux-en-Y drainage since this is frequently complicated by infection (51). oResection/fenestration (41,53,54). In some series, however, PKD is a poor indication for resectional treatment and preference is given to liver transplantation (55). Previous surgery and immunosuppression are predictors of an unfavorable outcome (53). This should be taken into consideration in particular in patients on hemodialysis and who are candidates for renal transplantation. Nevertheless, this is the method of choice for symptomatic patients with massive liver disease; satisfactory relief can be obtained in over 90 % of patients when appropriately selected (56). oLaparoscopic fenestration without (57) or with alcohol instillation (58). After laparoscopic unroofing, recurrent symptoms are observed in up to 60 % of patients and some patients have to be converted to open laparotomy (57); in the quoted series patients with superficial large cysts benefited most from laparoscopy. oLiver transplantation in selected cases (59-62). oAscites has been successfully treated with peritoneovenous shunting (38). Nowadays, in particular when it is occurring after surgical interventions, preference should be given to somatostatin (63).
http://www.lib.siu.edu/websites/health/mradiogr.html