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Definition of AIDS Cholangiopathy
Patients with AIDS can develop an abnormality of liver enzymes and sclerosing cholangitis. Alkaline phosphatase (ALP) is usually elevated, while CD4 count is always < 200 x 106/L. This form of sclerosing cholangitis is believed to be related to opportunistic infections in AIDS and is known as AIDS cholangiopathy.
Epidemiology and Etiology of AIDS Cholangiopathy
AIDS cholangiopathy is a fatal complication of AIDS that has become very rare since the introduction of highly active antiretroviral therapy (HAART). The median survival after the diagnosis of AIDS cholangiopathy is about 9 months. Patients who are HIV positive are expected to develop some liver abnormalities, but the diagnosis of AIDS cholangiopathy is reserved for patients with sclerosing cholangitis.
The most common etiology of AIDS cholangiopathy is infectious. Opportunistic infections of the biliary system are responsible for AIDS-related cholangitis and sclerosing cholangitis in this group of patients.
The most commonly identified organisms are cryptosporidium and cytomegalovirus, which can be isolated from the bile. Enterocytozoon bieneusi can also be identified in the bile of some patients with unexplained AIDS cholangiopathy.
Pathophysiology and Clinical Presentation of AIDS Cholangiopathy
Patients with AIDS cholangiopathy have a very low CD4 count that is lower than 200 x 106/L, which puts them at risk of opportunistic infections. Opportunistic infections of the biliary system result in scarring and elevated liver enzymes such as alkaline phosphatase. Eventually, sclerosing cholangitis ensue and patients can develop chronic liver disease.
Patients with AIDS cholangiopathy usually present with right upper abdominal pain and elevated liver enzymes. Abdominal pain is usually associated with nausea, vomiting and fever. Jaundice is rarely seen in AIDS cholangiopathy.
Diagnostic Work-up for AIDS Cholangiopathy
The incidental finding of an elevated alkaline phosphatase level in a patient with AIDS can be a presenting feature of AIDS cholangiopathy. A complete blood count always reveals a CD4 count < 200 cells/ mm3 and usually lower than 100 cells / mm3. Other hepatic enzymes can be abnormal in patients with AIDS cholangiopathy but this finding is not specific. Bilirubin is usually normal, hence there is typically no jaundice present on physical examination.
Transabdominal ultrasound is indicated as a first-step diagnostic tool in the evaluation of patients where the differential of AIDS cholangitis is being considered.
Findings consistent with sclerosing cholangitis on transabdominal ultrasound, include:
- dilated intrahepatic bile ducts,
- stenosis and thickening of the common bile duct wall.
If any of these findings are identified in a patient with AIDS, an endoscopic retrograde cholangiopancreatography (ERCP) is indicated.
ERCP is the gold standard, diagnostic modality for AIDS cholangiography. Sclerosing cholangitis, intrahepatic sclerosing cholangitis, and extrahepatic bile duct strictures are usually evident on ERCP in patients with AIDS cholangiopathy. An abnormal ultrasonography study is highly predictive of an abnormal ERCP result in patients with AIDS cholangiopathy.
Other less commonly used imaging modalities include computerized tomography (CT) scanning and hepatobiliary scintigraphy. CT scanning of the biliary system can reveal intrahepatic ductal dilation but is not sensitive enough to diagnose increased extrahepatic bile ductal wall thickness. Hepatobiliary scintigraphy can identify intrahepatic and extrahepatic sclerosing, stenotic and dilation abnormalities.
Treatment of AIDS Cholangiopathy
A holistic approach to treating AIDS cholangiopathy is critical and includes:
- diet and lifestyle modifications,
- antimicrobial and antiviral therapy,
- ERCP, and
- palliative pain control, when appropriate.
Current consensus is that AIDS cholangiopathy is infectious in origin, hence diet modifications are not very beneficial. Sexual education about safe-sex practices can lower the risk of HIV infection and AIDS.
Unfortunately, patients with AIDS cholangiopathy do not benefit from antimicrobial therapy unless the etiology is related to cryptosporidium infection. Few studies have reported a clinical improvement and bile clearance of oocysts in patients with AIDS cholangiopathy due to cryptosporidium infection when intravenous paromomycin followed by oral letrazuril was given.
Gastrointestinal symptoms related to cryptosporidium infection such as diarrhea and abdominal pain may be alleviated with antimicrobial therapy.
There is no current treatment for patients with cytomegalovirus-related AIDS cholangiopathy. Patients who develop cholecystitis as a complication of AIDS cholangiopathy benefit from trimethoprim-sulfamethoxazole because the most commonly implicated organism is cyclospora cayetanensis, which is sensitive to trimethoprim-sulfamethoxazole.
The best treatment to lower the risk of AIDS cholangiopathy is HAART, which improves the immune function in patients with HIV infection. Additionally, patients with cryptosporidiosis infection benefit from HAART as it was shown to eradicate the organism oocysts in the stool.
HAART can also eradicate cryptosporidiosis oocysts from the bile in patients with AIDS cholangiopathy. HAART is also effective in patients with AIDS cholangiopathy who did not respond to antimicrobial therapy especially if a protease inhibitor is included.
HAART is not only effective in treating AIDS cholangiopathy, but can also lower the risk of AIDS and AIDS-defining disease. HAART also results in an improvement in the liver function, as manifested as a decrease in alkaline phosphatase and a reduction in the diameter of intrahepatic and extrahepatic bile ductal system.
Therapeutic ERCP is indicated for patients who have stenosis in the papilla of Vater as urgent biliary decompression and drainage is usually needed. Unfortunately, ERCP does not affect survival in patients with AIDS cholangiopathy and HAART is the only treatment that was found to directly increase survival.
ERCP usually results in significant improvement in symptoms attributed to AIDS cholangiopathy such as abdominal pain and fever, but is not known to affect liver chemistry or decrease alkaline phosphatase.
Finally, patients with AIDS cholangiopathy may develop medically intractable abdominal pain. In these situations, a celiac plexus block may be beneficial for pain relief. However, this interventional treatment is typically reserved for patients with AIDS-related sclerosing cholangitis associated with papilla of Vater stenosis that is unresponsive to narcotics or ERCP treatment.
Patients with acalculous cholecystitis related to AIDS cholangiopathy might benefit from a laparoscopic cholecystectomy, particularly when ERCP, HAART and antimicrobial therapy are ineffective.