Intracranial epidermoid and dermoid tumors are unusual benign lesions that are potentially curable. Subtotal removal carries a high incidence of recurrence, plus the rare possibility of carcinomatous degeneration of the remnants. Aseptic meningitis from spillage of cyst contents into the subarachnoid space is frequent after operation and has been reported to occur spontaneously. A case of a patient with a posterior fossa epidermoid cyst presenting with multiple bouts of aseptic meningitis in which squamous cell carcinoma arose in recurrent tumor 5 years after subtotal removal of the benign lesion is described.
Malignant transformation in a craniopharyngioma has not been described previously. A 49-year-old woman presented with recurrence of a suprasellar craniopharyngioma diagnosed 35 years previously. The patient had been treated surgically for recurrence on five occasions. Radiation therapy had been administered 7 years before the final presentation. Tissue obtained from the fifth operation revealed malignant degeneration in a typical craniopharyngioma.
Results from studies designed to create a model of focal encephalitis caused by herpes simplex virus (HSV) are reported. Anesthetized rabbits underwent exposure and inoculation of the olfactory bulb with three different doses of a wild-type HSV. Lethal infection resulted in 69% of the animals, without evidence for a dose-response relationship. Necropsy specimens obtained on or before day 10 after inoculation routinely yielded HSV in culture. In 76% of the animals with positive cultures for virus, these cultures originated exclusively or primarily from the pyriform (or temporal) cortex and frontal lobes. Virus could not be cultured from animals killed more than two weeks after inoculation. Histological examination of brains obtained three or more days after inoculation demonstrated evidence of viral infection, with more severe involvement of temporal cortex than of the surrounding brain in 80%. Immunohistochemical demonstration of viral antigens persisted for up to three weeks after inoculation.
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