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| Toxoplasmosis |
| Etiology •The protozoan Toxoplasma gondii invading the brain. |
| Pathogenesis •Toxoplasma encephalitis affects patients with defects in antibodies and delayed hypersensitivity as in utero fetuses and AIDS patients., |
| Epidemiology •Toxoplasmosis can be congenital or acquired. •Children and adults with a normal immune system only have minor symptoms if they acquire toxoplasma. •However, neonates can develop hydrocephalus, periventricular calcifications, and chorioretinitis if exposed in utero. •In HIV infected patients toxoplasma can cause a focal infection in the brain. |
| General Gross Description •In AIDS patients, the toxoplasma lesion presents as a mass lesion; in fact, it is the most comman mass lesion of the brain in this disease. •It usually appears as hemorrhagic and necrotic without a capsule but associated with a considerable amount of edema. |
| General Microscopic Description •Microscopically, toxoplasma has a necrotic appearance with neutrophils, macrophages and a few lymphocytes about it as well as sometimes quite bizarre reactive astrocytes. •In congenital infections there are periventricular calcifications and gliosis with gliosis extending to many other areas of the brain. •In both cases toxoplasma cysts or tachyzoites must be seen to make the diagnosis on tissue sections. •It can also be make serologically. |
| Clinical Correlation •In congenital lesions the gliosis and calcifications are usually associated with profound mental retardation. •In AIDS patients the toxoplasma abscess with its edema acts as a mass lesion, producing symptoms according to the area affected. •In the left speech areas it may cause aphasia, in the cerebellum, ataxia etc. |
| References • Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 229, 1325-1326. • Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp. 112. |
| Toxoplasmosis |
| Synopsis by: Dr ML Grunnet (TX2000E43360)[603] |
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