Cryptococcus meningoencephalitis in AIDS: parenchymal and meningeal forms

CT and MRI in one case of Cryptococcus neoformans infection showed contrast -enhancing parenchymal lesions resembling granulomata or abscesses. After a n initial phase without contrast enhancement, the full extent of the lesion s was visible within 2 weeks of presentation. The enhancing masses were ass umed to represent intracerebral cryptococcomas. Despite evidence of massive meningeal infection on cerebrospinal fluid (CSF) examination, no radiologi cal signs of meningitis, invasion of the Virchow-Robin spaces or ventriculi tis could be demonstrated. With antimycotic treatment the contrast enhancem ent disappeared and cystic, partly calcified lesions remained. Recurrence o f meningeal infection without radiological correlates was apparent in this stage. In a second case of proven cryptococcus meningitis, dilation of Virc how-Robin spaces or cysts in the adjacent parenchyma were the main abnormal ities on MRI. Enhancing masses were not detected. These cases may represent two different reactions of the immunocompromised hosts to infection with C . neoformans: widening of the perivascular spaces as a correlate of the mor e typical meningeal infection and enhancing parenchymal lesions as a sign o f further invasion from the CSF spaces. Enhancement of cryptococcomas, indi cating an inflammatory response in the surrounding brain, is not typical in patients with impairment of immune function.