Liver cysts and abscesses
De-roofing of liver cyst
(also called fenestration)
Diagram of cyst
arising from the liver
The term cyst means a collection of fluid that is surrounded by a lining that is producing that fluid. Many people have simple benign liver cysts that are seen on scans done for other reasons. These do not need treatment unless they are causing symptoms. Sometimes, patients have several liver cysts, and these may be part of a condition called polycystic liver disease. Occasionally, a cyst may actually be a tumour that is secreting fluid, and these are called cystadenoma or cystadenocarcinoma. If the scan appearances suggest that a cyst may be a tumour rather than a simple cyst, then further tests and surgical removal may be warranted.
Occasionally, if a simple benign cyst gets very large and begins to cause discomfort or other symptoms, then it can be treated by an operation that is called fenestration, quite akin to taking the top off a large blister. This is often done by a laparoscopic (keyhole) approach.
Some liver cysts can result from a parasitic infection. The dog tapeworm (known as Echinococcus granulosus) normally lives in the gut of dogs, and releases its eggs in the dog’s droppings. Sheep that graze on pastures with dog droppings on them ingest these eggs, and the larvae of the worm then grow in the sheep’s liver and form cysts. When an infected sheep dies and a dog eats the infected offal, the worm grows in the gut of the dog, and its life cycle is complete. Humans who handle dogs, especially in parts of the world where sheep-rearing is common, can inadvertently pick up this infection, and develop parasitic cysts within their livers. These are called Hydatid cysts. They usually have a typical appearance on ultrasound and CT scans. Active cysts will usually contain a number of daughter cysts within them. A blood test for antibodies to the parasite can often tell if the patient has this infection. Treatment is required, to prevent further growth and rupture of the cysts. It involves taking an anti-parasitic drug such as Albendazole, and the course lasts several months. This may kill off the parasite but it will not make the cyst disappear. Cysts that are very large or grow despite drug therapy, or cause symptoms, or press on surrounding structures, or have developed additional bacterial infection (i.e. become an abscess) need additional treatment. This may involve injection of concentrated saline into the cyst cavity (to kill the parasite), and in some instances, surgery to de-roof the cyst or cut out that part of the liver i.e. a liver resection. In so doing, one has to be very careful not to spill any of the cyst fluid into the abdominal cavity.
The term abscess means a collection of pus. Bacteria that cause abscesses usually get to the liver through the blood circulation, and the bowel is often the source where these bacteria have come from. A liver abscess can cause fever and pain in the upper abdomen and the right flank. The diagnosis is made from an ultrasound or CT scan. Treatment involves antibiotics, and drawing out the pus under ultrasound guidance. One should look for the source of the infection especially in the large bowel. Very rarely a tumour can masquerade as an abscess.
Amoebic liver abscess
Entamoeba histolytica is a gut parasite, common in the tropics, and the cause of amoebic dysentery. But it can spread from the gut to the liver though the blood stream, and cause the formation of an abscess within the liver. Treatment involves anti-amoebic medication such as metronidazole, and occasionally drainage of the pus under ultrasound guidance.