Pathology of the Endocardium
Non-bacterial Thrombotic Endocarditis
Non-bacterial thrombotic endocarditis has been reported with increasing frequency in HIV-infected patients in the terminal stage of the disease.
This process, commonly associated with chronic severe wasting diseases, particularly malignancies, and severe inanition, was observed before the introduction of HAART in 3-5% of AIDS patients at autopsy [1-3].Pathologic Findings
Non-bacterial thrombotic endocarditis can involve all four cardiac valves [2]. Macroscopic examination reveals thrombi adherent to the endocardial surface of the valve cusps, consisting microscopically of platelets within a fibrin mesh with few inflammatory cells. Thrombotic vegetations may be either single or multiple polypoid masses, along the cusp apposition lines. The valve often shows changes due to previous inflammatory or dystrophic lesions [3].
Thrombotic vegetations of non-bacterial thrombotic endocarditis are similar to those found in infective endocarditis; the differential diagnosis is based on the absence of the other typical features of infective endocarditis such as destruction and erosion of the cusp edges with tears and perforations through the body of the cusp itself, and valvular leaflet aneurysmal sacs [3]. Moreover, no infective pathogens are detected on histological examination. Systemic or pulmonary embolization of vegetations is usually detected at autopsy (more than 40% of patients with non-bacterial thrombotic endocarditis) and is underestimated clinically. Often, clinical symptoms of systemic thromboembolization (cerebral, pulmonary, renal, and splenic infarcts) make the valvular lesions clinically obvious. However, systemic thromboembolic disease due to non-bacterial thrombotic endocarditis is a rare cause of death (7%) in AIDS patients [1]. The vegetations in non-bacterial thrombotic endocarditis may be infected by pyogenic or fungal pathogens during a transient bacteremia, bringing about a typical infective endocarditis.