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dropout of tubular epithelial cells, loss of brush borders, and thickening of tubular basement
membranes. There can be interstitial fibrosis.[257] Toxicity may result in microscopic proximal
tubular eosinophilic inclusions that represent giant mitochondria that by electron microscopy
show dysmorphic changes. The tubular damage may be reversible if the drug is stopped.[933]

OPPORTUNISTIC INFECTIONS.-- These infections most commonly involve the renal
interstitium in either cortex or medulla. Small inflammatory infiltrates composed of
lymphocytes or macrophages usually accompany infection with C neoformans, H capsulatum, T
gondii, or cytomegalovirus. M tuberculosis and C immitis may produce granulomas.
Mycobacterium avium-complex produces small clusters of pale striated blue macrophages with
hematoxylin-eosin staining. Candida produces small microabscesses, but renal abscesses may
be present in up to 5% of AIDS patients with bacterial sepsis. Sometimes, small numbers of
budding cells of fungal organisms can be seen within glomeruli, often without marked
inflammatory reaction. Cytomegalovirus involves renal tubular epithelium in about half of cases
with renal involvement by CMV. In remaining cases, the CMV cells may be found in the
interstitium or, less commonly, the glomerulus. Cytomegalovirus in kidney may be
accompanied by focal chronic inflammatory cell infiltrates.
BK virus, a member of the human polyoma virus group, may be reactivated with
immunosuppression. It can produce a tubulointerstitial nephritis. Renal biopsy may show
intranuclear inclusions within renal tubular cells. BK viral DNA may be detected with in situ
hybridization.[934] BK viremia is not common with HIV infection, but BK viruria occurs in
about half of infected patients, more often when the CD4 count is above 500 and HIV viremia is
low, and there is no correlation with renal or neurologic disease.[935]

URINARY TRACT NEOPLASMS.-- AIDS-associated neoplasms in the kidney occur
when there is widespread involvement of multiple organs. Kaposi's sarcoma produces a few
widely scattered small red to red-purple nodules anywhere from the perirenal fat to the renal
capsule to the collecting system. One peculiar pattern of renal involvement seen in about half of
cases with high grade lymphomas in AIDS is the appearance of one or several prominent mass
lesions from 1 to 5 cm in size. These masses are firm, discrete, and have a white to minimally
variegated red-white, lobulated cut surface. In remaining cases, the lymphomatous infiltrates are
faintly visible to inconspicuous grossly.
Bladder carcinoma may occur in association with HIV infection, typically urothelial
carcinoma. These carcinomas in HIV-infected persons tend to occur at a younger age and with
only mild immunosuppression. Hematuria is the usual presenting sign.[936]

MALE GENITAL TRACT.-- About half of male AIDS patients have clinical evidence of
gonadal dysfunction with decreased libido and impotence that may be explained by decreased
testosterone levels. The exact mechanism is not entirely clear. Both ganciclovir used to treat
cytomegaloviral infections and ketoconazole used to treat fungal infections may decrease
testosterone synthesis.[864] There are no specific pathologic changes in the male genital tract
resulting from HIV infection despite the fact that seminal fluid is a common vehicle for
transmission of HIV. By in situ hybridization, HIV-1 proviral DNA can be identified within the
germ cells at all stages of differentiation but without morphologic changes.[937]
Immunohistochemical staining with anti-HIV monoclonal antibody has demonstrated the
presence of HIV in both testis and prostate.[938]