FOCAL BRAIN-LESIONS IN PATIENTS WITH AIDS - ETIOLOGIES AND CORRESPONDING RADIOLOGICAL PATTERNS IN A PROSPECTIVE-STUDY

We report the results of a hospital-based study of 188 consecutive pat ients seropositive for the human immune deficiency virus type 1 (HIV-1 ) who presented in a 4-year period (1988-1991) with possible signs or symptoms of first-ever central nervous system disease. Confirmed diagn oses were cerebral toxoplasmosis in 47 patients (25.0%), HIV-1 encepha lopathy in 19 (10.1%), progressive multifocal leucoencephalopathy (PML ) in 9 (4.8%), cerebral lymphoma in 1 (0.5%), and other conditions in 9 patients (4.8%). Seventy-three subjects (38.8%) showed focal brain l esions on initial computed tomography or magnetic resonance imaging, w hich were assessed prospectively. Positive predictivity for toxoplasmo sis was 100% if multiple lesions occurred in combination with mass eff ect or contrast enhancement (23 patients), or if at least one space-oc cupying or enhancing lesion was located in the basal ganglia or the th alamus (26 patients). Solitary lesions with mass effect or contrast en hancement were seen in 26 patients and were caused by cerebral toxopla smosis in 22 (84.6%). Eight of the 9 PML patients presented with one o r more non-enhancing, non-mass lesions, although the predictive Value of this pattern was low (47.1% for PML). Thus, in our epidemiological context, certain imaging findings in HIV-1-seropositive patients were highly predictive of cerebral toxoplasmosis. This may differ from find ings from other parts of the world where cerebral toxoplasmosis may be less prevalent among HIV-1-infected individuals.