Anorectal disease

Perianal discomfort is often caused by recurrent herpes simplex infection. The diagnosis should be confirmed by viral culture. Patient-initiated intermittent aciclovir can give adequate symptom control in some cases but many patients will require long-term maintenance therapy.

Anal warts are common but rarely cause much in the way of symptoms and should be treated on merit given the absence of any effective antiviral therapy. Anal intraepithelial neoplasia has been described in association with human papillomavirus infection but reports of invasive malignancy are still infrequent.

Patients may present with a mucopurulent proctitis, possible causes of which include recently acquired or long-standing Neisseria gonorrhoeae or Chlamydia trachomatis infection.

Figure 7.5 ERCP of AIDS sclerosing cholangitis with intrahepatic biliary tract distortion and dilatation of the common bile duct

Box 7.4 Differential diagnosis of liver disease

• Hepatitis or cholestasis

• M. avium-intracellulare complex

• Drug-induced

• Viral hepatitis

• Cytomegalovirus

• Mycobacterium tuberculosis

• Cryptococcus

• Microsporidia

• Lymphoma

• Kaposi's sarcoma

• Biliary disease

• Cryptosporidium

• Cytomegalovirus

• Microsporidia

• Lymphoma

• Kaposi's sarcoma

Figure 7.6 Aciclovir-resistant perianal herpes simplex infection

Neoplasia

Kaposi's sarcoma (KS) is commonly seen in the gastrointestinal tract and occurs in homosexual men more frequently than in patients from other risk groups. A new human herpes virus (HHV8) or Kaposi's sarcoma-associated herpes virus (KSHV) has been recently identified as a likely aetiological agent.

Lymphoma is much less common than KS however, although the incidence of KS has decreased along with the incidence of life-threatening opportunistic infections in association with the introduction of highly active antiretroviral therapy. The incidence of lymphoma has not been affected. HIV-associated lymphomas are usually high grade non­Hodgkin's type, of B-cell origin. Extranodal involvement is typical and the gut is one of the commonest sites involved.

We thank Dr Wilfred Weinstein, UCLA Medical School, Los Angeles for providing the photograph of oesophageal candidiasis and Dr David Casemore, PHLS Glan Clwyd, North Wales for the electronmicrograph of cryptosporidium.

Figure 7.7 Discrete lesion of Kaposi's sarcoma in the rectum

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