Physical examination revealed an enlarged liver, palpable 3 cm below the right costal margin. Pertinent laboratory investigation was as follows: Complete blood count and routine biochemical analysis revealed as; hemoglobin: 14.1 g/dl, leukocyte count: 12.700 /mm3, platelet count: 220.000 /mm3, blood urea nitrogen: 34 mg/dl, creatinine: 0.7 mg/dl, total bilirubine: 0.6 mg/dl, alanine aminotransferase: 8 U/l, aspartate aminotransferase: 20 U/l, alkaline phosphatase: 121 U/l. Urin analysis was normal.

Plain x-ray of the abdomen was unremarkable. Abdominal ultrasonography showed hepatomegaly, multiple dilated intrahepatic bile ducts and multiple cystic dilatations within both kidneys. Computed tomography of the abdomen indicated cystic images distributed in both lobes of the liver and multiple medullary cysts within the kidneys (Figure 1). Magnetic resonance cholangiopancreatography (MRCP) was performed, which pointed out multiple cystic dilatation of the intrahepatic duct (Figure 2). The main bile duct and extrahepatic bile ducts were normal.

Figure 1: CT scans showing cysts in liver and in kidneys.

Figure 2: MRCP showing cystic dilatations of the intrahepaticbile duct.

Based on these clinical and laboratory findings, he was diagnosed as Caroli's syndrome with medullary sponge kidney, and then he has currently being followed up at our out-patient department for the complications of Caroli's syndrome.

The clinical manifestations of Caroli's syndrome are related to the biliary abnormalities and portal hypertension⁷. There are several clinical presentations depending on the age of onset and the predominance of hepatic or renal involvement. In both Caroli's disease and syndrome, the saccular or fusiform dilatation of bile ducts predisposes to stagnation of bile leading to the formation of biliary sludge and intraductal lithiasis. Bacterial cholangitis occurs frequently and may be complicated by septicemia and hepatic abscess². Patients with Caroli's syndrome can present with portal hypertension and its squeal, such as ascites and esophageal variceal hemorrhage. Other patients present only with intermittent abdominal pain. Pruritus is common.

On physical examination, the liver is frequently enlarged. Patients with renal involvement may also have enlarged kidneys, which may be palpable. Laboratory studies typically show an elevation of serum alkaline phosphatase, direct billirubin, and a leukocytosis with a predominance of neutrophils. Hepatic synthetic function is well preserved initially, but may be affected by progressive liver damage due to recurrent cholangitis and biliary obstruction. Coagulopathy from vitamin K malabsorption may occur in cholestatic patients^8,9.

The diagnosis of Caroli's disease and Caroli's syndrome is established by imaging studies that demonstrate bile duct ectasia and irregular, cystic dilation of the large proximal intrahepatic bile ducts with a normal common bile duct. These findings can readily be identified with ultrasonography, endoscopic retrograde cholangiopancreatography, or magnetic resonance imaging which can also demonstrates the renal features of cystic disease^2,6. A liver biopsy is rarely required for the diagnosis.

Renal lesions and choledocal cysts are the associated conditions with Caroli's syndrome. Renal anomalies include renal tubular ectasia (medullary sponge kidney, cortical cyst), adult recessive polycystic kidney disease, and rarely autosomal dominant polycystic kidney disease^10,11. Medullary sponge kidney is described by ectatic and cystic malformations of the collecting ducts and tubules of one or more papillae of one or both kidneys. These anatomic abnormalities produce no symptoms. The morbidity of this disorder is the result from nephrolithiasis and urinary tract infection, both of which are thought to be secondary to the anatomic abnormalities¹².

There is no curative treatment for Caroli's disease. Treatment is mainly supportive and should be individualized. Cholangitis and sepsis are treated with appropriate antibiotics and biliary stone extraction whenever feasible⁵. Endoscopic sphincterotomy and stone extraction can be used to remove common duct stones. In contrast, the extraction of intrahepatic stones is far more difficult⁵. Patients, who have recurrent attacks of biliary infection, particulary those who also have complications related to portal hypertension, may need liver transplantation⁷. Patients who have developed esophageal varices should receive prophylaxis with a non-selective beta blocker¹³. A selective shunting procedure can provide relief from portal hypertension if liver function may be well preserved¹⁴. Unexplained clinical deterioration or the appearance of a new biliary stricture should raise a concern that cholangiocarcinoma has developed¹⁵.

Asymptomatic patients with medullary sponge kidney require no specific therapy except to maintain high fluid intake to reduce the risk of nephrolithiasis. Infection should be treated aggressively, and instrumentation of the urinary tract should be minimized to avoid infection. The prognosis is variable depending on the severity of liver disease and the presence of coexisting renal dysfunction. Since the risk of cholangiocarcinoma is increased up to 7 percent, screening for this complication important¹⁶.

Our patient exhibited clinical and radiologic findings for Caroli's syndrome with medullary sponge kidney. The absence of symptom and laboratory finding of hepatic or renal dysfunction enabled us to keep track progress and observe him until the development of complication.