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Diagnosis of chagasic tumor-like lesions

In patients with cerebral mass lesions, neuroimages typically show one or more ring-enhancing lesions involving both gray and white matter, the cerebellum and the brain steam.56-58 Magnetic resonance imaging (MRI) and cranial computed tomography (CT) reveal single or multiple tumor-like lesions with hypodense or

Axial Tl-weighted MRI showing a heterogeneous right parieto-occipital lesion with irregular gadolinium enhancement, mass effect on the middle line structures, and perilesional edema (arrow)

Figure 30.6 Axial Tl-weighted MRI showing a heterogeneous right parieto-occipital lesion with irregular gadolinium enhancement, mass effect on the middle line structures, and perilesional edema (arrow).

hypointense centers, with or without contrast enhancement, with or without areas of perilesional edema, and with or without effect on the middle line structures (Fig. 30.6). This imaging pattern of brain chagoma is similar and indistinguishable to that cerebral toxoplasmosis.39,40,54 MRI spectroscopy showed a significant increase in choline/creatine ratios (Cho/cr) associated with an increased membrane synthesis and the pathological evidence of lipid or lactate signals related to the presence of anaerobiosis or necrosis in the central area of the abscess (Fig. 30.7). In endemic areas for T. cruzi infection, all HIV patients presenting with cerebral brain lesions should be evaluated for specific anti-T. cruzi antibodies and for parasitemia (Fig. 30.4).59

When T. cruzi trypomastigotes cannot be demonstrated in the CSF, a cerebral biopsy of focal brain lesions may be necessary. Histopathological findings include a granulomatous abscess with necrosis, cerebral edema with focal necrotizing and hemorrhagic encephalitis with uni- or multifocal lesions of undefined limits containing amastigotes of T. cruzi in Giemsa smears (Fig. 30.8).60 The most striking finding is the presence of many small organisms within the macrophages (amasti- gotes). Electron microscopic features of the organism include parallel microtubules under the cell membrane, a kinetoplast, and a flagellar pocket containing a rudimentary flagellae.6l These lesions are generally localized at the brain periphery, affecting the gray and, especially, the white matter. Lesions can also occur in the brainstem and in the cerebellum.62

The absence of anti-Toxoplasma antibodies in patients with HIV infection who have one or more expansive lesions should raise clinical suspicion of alternative diseases, including Chagas disease. The presence of anti-T. cruzi antibodies is

MRI spectroscopy in axial Tl-weighted with a single voxel localized at the lesion and corresponding to the patient of Fig

Figure 30.7 MRI spectroscopy in axial Tl-weighted with a single voxel localized at the lesion and corresponding to the patient of Fig. 30.6. Significant increase in choline/creatine ratios (Cho/cr) associated with an increased membrane synthesis and the pathological evidence of lipid signal related to the presence of anaerobiosis or necrosis.

Diagnosis algorithm of cerebral abscesses in AIDS patients

Figure 30.8 Diagnosis algorithm of cerebral abscesses in AIDS patients.

important in the initial approach. The mortality rate is approximately 85%, even in patients receiving treatment, mainly due to delayed diagnosis and severe immunosuppression.63

 
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