Liver cysts occur in approximately 5% of the population. However, only about 5% of these patients ever develop symptoms. In general, cysts are thin-walled structures that contain fluid. Most cysts are single, although some patients may have several. The symptoms associated with liver cysts include upper abdominal fullness, discomfort, or pain. A small number of patients bleed into the cyst, which causes sudden and severe right upper quadrant and shoulder pain. The bleeding stops on its own, and the pain then improves over the next several days. Liver cysts do not impair the liver’s ability to function. The cyst(s) are usually found by ultrasound (US) or computed tomography (CT scan). Simple liver cysts are always benign. The only patients who require treatment for a liver cyst(s) are those who develop symptoms. Simply removing the fluid from the cyst with a needle is not effective because the cyst fills up again within several days. The best treatment is to remove a large portion of the cyst wall. This surgical procedure can usually be done through the laparoscope, which requires only 2-3 small incisions and an overnight stay in the hospital. Most patients recover fully within 2 weeks. The risk of the cyst recurring is very low. A very small number of patients (0.6% of the general population) have polycystic liver (PLD) disease, which is characterized by the liver appearing like a cluster of very large grapes. Over the course of several years, patients with PLD may develop massive enlargement of the liver, which results in abdominal swelling and discomfort. In extreme cases, the patient may have a very poor quality of life because of the pain and fluid. Unlike the inevitable kidney failure associated with polycystic kidney disease, which can coexist with PLD, PLD does not cause liver failure. The only long-term solution for patients with severe PLD is liver transplantation.
Unlike simple liver cysts, cystic tumors are actually growths that may become malignant over the course of many years. The benign cystic tumor seen most frequently is called a cystadenoma; its malignant counterpart is a cystadenocarcinoma. The symptoms caused by cystic tumors are the same as those seen with simple cysts; fullness, discomfort, and pain. The liver blood tests usually remain normal, unless a cancer has developed. US and CT scans are the best imaging studies to show the cystic tumors, which contain both liquid and solid areas. Because of the possibility of malignancy, cystic tumors must be completely removed surgically with an open (not laparoscopic) operation. The recurrence rate after surgery is very low and the long-term prognosis is excellent.