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MYCOBACTERIA.-- Mycobacterium avium complex (MAC) is the most frequent
opportunistic infection involving the liver, found in slightly less than half of AIDS cases in
which MAC is diagnosed. Associated clinical findings include fever and weight loss.
Transaminases may be two to three times normal. Mycobacterium avium complex infection
results in moderate to marked hepatomegaly but rarely produces grossly visible lesions. Tiny
echogenic foci may appear on ultrasonography of the liver, though occasional larger lesions may
be hypoechoic by ultrasound or show low attenuation by computed tomography.[416] The
microscopic pattern of involvement consists of small clusters of striated blue macrophages with
hematoxylin-eosin staining (and numerous acid-fast bacilli) scattered throughout the parenchyma
in a portal to midzonal distribution. Adjacent liver parenchyma appears normal. Obstruction
does not occur. Mycobacterium tuberculosis may be seen in liver with dissemination and
produces small tan to white granulomas that are unlikely to result in hepatomegaly. The
microscopic appearance of these granulomas includes typical features of necrosis, epithelioid
cells, lymphocytes, occasional Langhans giant cells, and scattered acid-fast bacilli.[874,873]

FUNGAL INFECTIONS.-- The fungi C neoformans, H capsulatum, and C immitis
involve the liver frequently in disseminated infections, may be associated with mild
abnormalities of liver function tests, but usually do not produce symptomatology from liver
disease. Hepatosplenomegaly is common. These organisms do not often produce grossly
conspicuous granulomas--discrete granulomas are present in less than 20% of involved livers
with histoplasmosis. Cryptococcosis is the most frequently identified fungus in liver, seen in
about one third of AIDS cases with C neoformans at autopsy (Table 5). These dimorphic fungi
are most likely to have an infiltrative pattern of involvement with small numbers of organisms in
portal areas. H capsulatum can be seen in clusters within macrophages. Accompanying
inflammatory infiltrates and necrosis are usually not prominent; portal lymphohistiocytic
infiltrates are the most common histologic finding.[669,873]

CYTOMEGALOVIRUS.-- Cytomegalovirus (CMV) can involve the liver in AIDS,
usually in association with disseminated infections, and patients are rarely symptomatic just from
hepatobiliary involvement. Alkaline phosphatase can be mildly elevated. A true CMV hepatitis
is rare. Rarely, a granuloma or mass lesion can be produced. The characteristic inclusion bodies
can appear in any cell in the liver, but they can be difficult to find.[872,873]

TOXOPLASMOSIS.-- T gondii are infrequently found and rarely produce a widespread
infection in liver. The only evidence of their presence may be a rare cytomegalic cell or T gondii
cyst found only after very careful searching at high power. A small focal collection of
inflammatory cells may accompany them. In rare cases, hepatitis with extensive necrosis may
occur.[872]

AMEBIASIS.-- In parts of the world with endemic Entamoeba histolytica infections,
there may be complications of amebiasis in patients with HIV infection. In one Taiwanese
study, half of cases of amebic liver abscess occurred in persons infected with HIV. In over half
of these patients, the CD4 count was above 200/µL.[882]

KAPOSI'S SARCOMA.-- AIDS patients with KS have liver involvement only one fifth
of the time (Table 5). The alkaline phosphatase is often elevated in these cases, because the