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KAPOSI SARCOMA.-- Kaposi sarcoma (KS), despite its vascular nature, is not often
seen in the heart (Table 5). Cardiac involvement by KS is often limited to small subepicardial
deposits in adipose tissue, which usually do not produce clinically apparent problems.
Microscopically, the appearance is no different from elsewhere, with atypical spindle cells
around vascular slits accompanied by red blood cell extravasation. When KS does involve the
heart, there is usually widespread visceral organ involvement, and pulmonary involvement will
probably be of greater significance.[900]

INFECTIONS.-- Elevation of creatine kinase (CK) may commonly occur with
myocardial toxoplasmosis. Toxoplasma gondii can produce a gross pattern of patchy irregular
white infiltrates in myocardium similar to non-Hodgkin lymphoma. Microscopically, the
myocardium shows scattered mixed inflammatory cell infiltrates with polymorphonuclear
leukocytes, macrophages, and lymphocytes. True T gondii cysts or pseudocysts containing
bradyzoites are often hard to find, even if inflammation is extensive. Immunohistochemical
staining may reveal free tachyzoites, otherwise difficult to distinguish, within the areas of
inflammation. T gondii myocarditis can produce focal myocardial fiber necrosis. Heart failure
can ensue. There may be regional differences in the incidence of T gondii myocarditis, perhaps
because the natural reservoir of organisms persists more easily in humid environments.[475]
Other opportunistic infections of heart are infrequent. They are often incidental findings
at autopsy, and cardiac involvement is probably the result of widespread dissemination, as
exemplified by Candida and by the dimorphic fungi Cryptococcus neoformans, Coccidioides
immitis, and Histoplasma capsulatum. Patients living in endemic areas for Trypanosoma cruzi
may rarely develop a pronounced myocarditis.[799] Cardiac opportunistic infectious lesions in
pediatric AIDS cases are not frequent.[899]

MYOCARDITIS.—A non-specific myocarditis composed mainly of mononuclear cells
appears much more commonly than infectious organisms in the heart of AIDS patients
microscopically. There is typically four-chamber dilation. There are mononuclear cells
distributed diffusely as single cells or in small clusters. Very minimal myocardial fiber ischemia
or necrosis usually accompanies the myocarditis. A myocarditis may be found in 17% of AIDS
cases at autopsy in association with cocaine use, and 10% without cocaine, and it usually occurs
in the absence of diagnosable opportunistic infections. Many AIDS patients with a history of
clinical cardiac abnormalities have myocarditis at autopsy. HIV itself may cause T lymphocyte
activation with cytokine release that potentiates myocardial damage. Histologically,
mononuclear cells may also be seen as a mild epicarditis, which may account for some
pericardial effusions. Findings more often seen with cocaine use, but also with HIV, include
coronary artery infiltrates, left ventricular hypertrophy, and thickened myocardial
vessels.[896,901]

AIDS CARDIOMYOPATHY.-- A congestive (dilated) cardiomyopathy in both adult
and pediatric AIDS patients has been identified in 10 to 30% of cases. Most of these cases are
idiopathic, for no specific opportunistic infection or neoplasm can be identified. Patients with
symptomatic heart failure from dilated cardiomyopathy typically present late in the course of
AIDS, have low CD4 counts, have myocarditis, and have a persistent elevation of anti-heart
antibodies. At autopsy, there is four-chamber dilation with a flabby, pale appearing
myocardium. Echocardiographic findings include four chamber enlargement, diffuse left