CNS INVOLVEMENT OF HIV:
- Cerebral involvement: AIDS dementia complex
- Multinucleate giant cells
- Vacuolar myelopathy
- HIV -1 associated neuronopathy is characterized by infiltration of macrophages into the CNS, formation of microglial nodule and multinucleated giant cell which result possibly from virus induced fusion of microglia and/macrophages in central white or gray matter
- Astrocyte activation and damage, neuronal loss particularly in Hippocampus, Basal ganglia, Caudate nucleus.
- Encephalitis: frontal /temporal cortical atrophy
- Meningitis with mild lymphocytic infiltrates and scanty perivascular inflammation
- Presence of microglial nodules
- Pericapillary aggregates of multinucleated giant cells having generous or scanty neoplasm
- Perivascular lymphocytic cuffing
- In leukoencephalopathy: there is diffuse demyelination and infiltration of macrophages and multinucleated giant cells.
- Microscopic findings of HIV encephalitis are :
- Diffuse white matter pallor
- Perivascular infiltrates of lymphocytes and macrophages
- Foci of necrosis, gliosis and / or demyelination
- Microglial nodules, macrophages and multinucleated cells
- Opportunistic infections of the CNS generally occur in HIV infected patients with CD4 counts below 200.
- Most common organism that causes acute meningitis in an AIDS patients is Cyptococcus neoformans.
- Caused By prion Protein
- Prions are proteins.
- They are infectious.
- Most common infectious prion disease in humans
- On light microscopy, the pathologic hallmarks of CJD are spongiform degeneration and astrogliosis.
- The lack of an inflammatory response in CJD and other prion diseases is an important pathologic feature of these degenerative disorders.
- Spongiform degeneration is characterized by many 1- to 5-um vacuoles in the neuropil between nerve cell bodies
- In (New variant ) nvCJD, a characteristic feature is the presence of "florid plaques." These are composed of a central core of PrP amyloid surrounded by vacuoles in a pattern suggesting petals on a flower.
- Corneal transplants
- EEG electrodes
- Dura mater grafts
- Human growth hormones from human pituitaries
- Deep white matter lesion consists of widespread acute disruption, or "shearing," of axons at the time of impact.
- Pathologically there are small areas of tissue disruption in the corpus callosum and dorsolateral pons. The presence of widespread axonal damage of both hemispheres, a state called Diffuse axonal injury, has been proposed as the explanation of persistent coma or vegetative state, but small ischemic-hemorrhagic lesions in the midbrain and low diencephalon are as often the cause.
- Only severe shearing lesions that contain blood are visualized by CT, usually in the corpus callosum and centrum semiovale however, within days of the injury,
- MRI scan demonstrates such lesions throughout the white matter, especially with the use of gradient echo MRI sequences.
|Origin from astrocytes|
|Most common primary brain tumor in adults|
|GFAP Positive||Origin From oligodendrocytes||Usually in ventricular system|
|Glioblastoma multiforme is grade IV astrocytoma||Fried Egg Appearance||Ependymal rosettes|
|Crosses midline||Chicken wire pattern of capillaries||Perivascular pseudorossettes|
|(Butterfly Glioma)||Slow growing||Often causes hydrocephalus|
- Primary CNS lymphoma is relatively common type of lymphoma in AIDS patients shows multicentric mass lesions in the brain and meninges derived from B-lymphocytes
- Presenting symptoms include seizures, headache, and cranial nerve deficits (e.g., the abducens nerve palsy in this patient). The lesions are often multicentric, and may involve the leptomeninges in a significant number of cases.
- Primary CNS lymphoma is typically a late manifestation of AIDS (median CD4 count 40/μl).
- This lymphoma is usually an intermediate-to-high-grade B cell lymphoma; evidence of Epstein- Barr virus infection is commonly present.Astrocytoma is a neoplasm derived from cells in the astrocyte lineage.
- Ependymal cells line the ventricles. Tumors derived from ependymal cells, called ependymomas, characteristically produce rosettes or perivascular pseudorosettes, microscopically. The incidence of ependymoma is not increased in AIDS patients.
- Melanoma is a neoplasm arising from transformation of melanocytic cells. Whereas the brain is a favorite site for metastatic melanoma, the incidence of melanoma is not particularly increased in AIDS patients.
- It may be due to:
- HIV encephalopathy(24-47%)
- Cerebral Toxoplasmosis(28%)
- Cerebral lymphoma(4%)
- Cryptococcal meningitis(13%)
- Progressive multifocal leukoencephalopathy(1%)
- It is due to Polyoma JC Virus
- It is mostly due to immunocompromised states.
- Demyelination and Astrogliosis are a feature
- These are B cell malignancies that present within the neuraxis without evidence of systemic lymphoma.
- They occur most frequently in immunocompromised individuals, specifically organ transplant recipients or patients with AIDS.
- In immunocompromised patients CNS lymphomas are invariably associated with Epstein - Barr virus (EBV) infection of the tumor cells.
- Treatment :> The mainstay of definitive therapy is chemotherapy including high-dose methotrexate. This is followed in patients < 60 years with radiotherapy. A single dose of rituximab is generally administered prior to cytotoxic chemotherapy
- Chemotherapy includes high-dose methotrexate, but multiagent chemotherapy, usually adding vincristine and procarbazine, appears to be more effective than methotrexate alone. Chemotherapy is followed in patients90% of patients develop recurrent CNS disease.
- Progressive multifocal leukoencephalopathy is the least common cause of seizures in AIDS
- Pathologic features of brain in AIDS includes microglial nodule, Pericapillary aggregates of multinucleated giant cells having generous or scanty neoplasm , Perivascular lymphocytic cuffing, demyelination and infiltration of macrophages and multinucleated giant cells.
- Cryptococcus neoformans is the most common cause of acute meningitis in an AIDS patient
- Primary CNS lymphoma shows multicentric mass lesions in the brain and meninges derived from B-lymphocytes
- Diffuse white matter pallor, Perivascular infiltrates of lymphocytes and macrophages, Foci of necrosis, gliosis and / or demyelination, Microglial nodules, macrophages and multinucleated cells e the Histopathological features of HIV encephalitis
- Perivascular lymphocytes & microglial nodules are seen in HIV encephalitis
- Primary CNS lymphoma is the Most common CNS neoplasm in HIV patient
- HIV associated neuronal loss occurs particularly in Hippocampus, Basal ganglia, Caudate nucleus.
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