Case Report: A 35-year-old man presented with sudden onset of acute abdominal pain in the right upper quadrant. He had been having progressively increasing yellowish discoloration of sclera, pale stools and generalized pruritis since several weeks. On examination, jaundice and mildly tender, mild hepatomegaly were the only positive findings. The vital signs were normal.

INVESTIGATIONS: Hb : 11.3 gm% ,TLC: 12800/cmm; Sr. bilirubin .: 25.9 mg %,

RADIOLOGICAL FINDINGS:

The patient was admitted and a CT scan was performed. This showed a cyst in segment 4 A & b with obstructive biliary dilatation. Reconstructed images clearly showed the cystic lesion in liver in communication with common the bile duct.
An MRI of the abdomen confirmed these findings.

An MRCP showed an approximately 7 cm diameter hypointense lesion in segments 4 a & b with linear hyperintense band within causing obstructive intrahepatic biliary dilatation.

The T2 weighted HASTE sequence showed a cystic lesion with septations within associated with obstructive biliary dilatation. The coronal images demonstrated communication of the cyst with the common bile duct.

Post contrast MR: showed peripheral enhancement of the cyst in segments 4 a & b with hypertrophy of the left lobe of the liver. The gall bladder was distended .The suprapancreatic common bile was dilated with gradual tapering of intrahepatic common bile duct.

A percutaneous trans-hepatic biliary drainage was performed.


However, the patient developed a peri-catheter leak and was operated with excavation of the cyst. A T tube was placed to drain the bile. The patient recovered well following the procedure and a T tube cholangiogram was performed. This showed a small residual cavity filled with contrast and no leak.

DISCUSSION:

Hepatic hydatid disease (HHD) is a major endemic problem in sheep-rearing regions of the world. Man is the incidental host affected accidentally when he comes into contact with food contaminated with dog feces or when he comes in close contact with sheep. The liver acts as a filter for hydatid larvae, making it the most commonly affected organ. Up to one-third of patients with HHD present with complications such as rupture (into the biliary tree, thorax or peritoneum), secondary infection, anaphylactic shock and sepsis. HHD disease is the commonest form of echinococcosis. The right lobe of the liver is affected in 80% of cases and the left lobe in 20% of cases. Rupture occurs into the right duct in 60% of cases, into the left duct in 30%. Intrabiliary rupture can lead to obstructive septic or allergic manifestations. Patients commonly present with right upper abdominal pain (82%), obstructive jaundice (57-100%), fever (70-90%), acute cholangitis (20-37%), abdominal lump (22-39%), and rarely with acute pancreatitis, liver abscess or septicaemia, or it may be asymptomatic (5-6%).

Lewall and McCorkell have classified rupture of echinococcal cysts into three types: contained, communicating and direct.

Ultrasound is the most commonly employed initial investigation. A complicated cyst has a multivesicular / multiseptate appearance with a heterogeneous echogenic interior. A dilated CBD in a jaundiced patient with a hydatid-like cystic lesion in the liver should prompt a diagnosis of intrabiliary rupture. Extrahepatic biliary dilatation is a constant feature. Echogenic or non-echogenic material without posterior acoustic shadowing is seen in the biliary tree, suggestive of sludge and daughter cysts.

The features of a hydatid cyst on CT are enhancement of the cyst wall and the internal septe; visualization of detached undulating membranes and calcification of the cyst wall. A dilated CBD with low attenuation intraluminal material suggests the presence of hydatid sand and cysts in the CBD. An interrupted area of the cyst wall proximal to a dilated duct may be identified as representing the site of communication. Cyst wall discontinuity - a direct sign of rupture, was seen in only 75% of cases. CT can demonstrates high attenuation material passing through the defect of the cystic wall and filling up the intrahepatic biliary radicles or CBD.

MRI is a useful tool in difficult cases such as intrabiliary rupture, where CT and ultrasound are not conclusive. The wall of the hydatid cyst is seen as a low intensity rim, a reliable sign to differentiate hydatid cyst from other simple cysts. Daughter cysts have a lower signal intensity compared with the mother cyst. The MRI finding in ruptured hydatid cyst can be direct or indirect. A breach in the low intensity rim of the cyst wall with extrusion of cyst contents is a direct sign, while increased echogenicity, fluid levels, presence of air and changes in signal intensity are indirect signs.

ERCP is the gold standard in confirming biliary tract involvement and may be of therapeutic benefit in selected cases. On ERCP, a swollen ampula of Vater may be seen, with hydatid material protruding out. Dilated ducts with debris and daughter cysts may appear as radiolucent filling defects. Irregular leaf-like material that changes shape with changes in pressure differentiates this condition from other causes of obstructive jaundice. A small cysto-biliary communication cannot always be excluded by ERCP and should be actively sought during surgery.

The usual findings in HIDA scan are photopenic areas in the liver in initial images, which gradually fills up in delayed images indicating bile leak into the cyst. Although it cannot document the exact nature of communication, HIDA can be helpful in doubtful cases with cysto-biliary communication where ultrasound and CT are not conclusive.

Surgery is considered the ideal treatment though percutaneous sclerotherapy has been used with varying success rates.