The liver is commonly involved during the course of HIV infection, with hepatomegaly and/or abnormal liver chemistry being seen in approximately 60% of AIDS patients. Involvement of the biliary tree and gallbladder is much less common. Hepatic disease may occur as a result of opportunistic infections (HSV, CMV, MAI, fungi) or neoplasms (KS, lymphoma). In such cases the liver is usually involved as part of more diffuse systemic involvement and is rarely the sole site of infection. Other infections such as hepatitis B and hepatitis C are common as a result of associated risk factors such as intravenous drug use and sexual transmission. Malnutrition, alcohol and hepatotoxicity of medications are other common factors that should be considered in the evaluation of hepatic abnormalities in these patients.

Co-infection of HIV with either hepatitis B or hepatitis C virus is often seen, as a result of common risk factors. The effect of HIV-related immunosuppression on chronic hepatitis B often results in clinical improvement of the chronic hepatitis. Since it is the immune reaction to hepatitis B that causes the hepatic inflammation, biochemical parameters of hepatitis often improve, as does the activity on liver biospy as the HIV-associated immunosuppression progresses. Despite the clinical improvement, hepatitis B viral replication increases. Hepatitis C, on the other hand, is directly hepatotoxic, and advancing immunosuppression is not uncommonly associated with worsening of the hepatitis and progressive liver disease. Treatment with interferon for either hepatitis B or C in this setting is generally associated with a poor response.

Biliary involvement in HIV infection is commonly termed AIDS cholangiopathy and results from inflammation of the biliary tree and gallbladder. There can be a spectrum of involvement ranging from acute acalculous cholecystitis to papillary stenosis with bile duct obstruction or more diffuse involvement of the biliary tree producing a picture similar to sclerosing cholangitis. Cholangiopathy is most commonly due to CMV infection of the biliary tree but has also been reported to result from biliary infection with Cryptosporidium or Microsporidium. Acute acalculous cholecystitis presents with RUQ pain, fever and tenderness on examination. Cholecystectomy is usually required. Cholangiopathy may present with less acute RUQ pain, fever and nausea, with cholestatic liver enzyme abnormalities. Diagnosis of cholangiopathy is made by ERCP. Patients with dilated common bile ducts who presumably have papillary stenosis secondary to an acute papillitis have responded symptomatically to endoscopic sphincterotomy. Patients in whom CMV is proven or suspected as the cause may improve with specific treatment for CMV. Rarely Kaposi's sarcoma or lymphoma can involve the gallbladder or biliary tree.

Symptomatic pancreatic involvement in HIV infection is not common, but clinically will usually present as acute pancreatitis. Asymptomatic elevations of serum amylase or lipase are common and are seen in up to 45% of patients. These are often related to medications but may also be due to asymptomatic involvement of the pancreas with opportunistic infection or neoplasm. Acute pancreatitis presents in a similar manner in patients with and without HIV infection. In addition to the commonly recognized causes of pancreatitis, other possibilities need to be considered in HIV patients. Drugs commonly used in HIV patients, including sulfonamides, pentamidine and the reverse transcriptase inhibitor dideoxyinosine (ddI), are common causes of pancreatitis. Pancreatic involvement with opportunistic infection and neoplasm, although usually asymptomatic, may cause pancreatitis. The principles of treatment of acute pancreatitis are the same for HIV-infected patients as for those without HIV infection. Drugs potentially involved should be stopped. Where no obvious etiology is apparent, CT scan of the pancreas is useful to rule out focal lesions that might indicate infections or neoplasms involving the pancreas.