Dentate nuclei involvement in AIDS patients with CNS cryptococcosis: imaging findings with pathologic correlation.

PURPOSE: Our goal was to describe the involvement of the dentate nuclei in AIDS patients with CNS cryptococcosis since this finding has not been emphasized in previous radiological literature.

METHOD: Plain and contrast-enhanced CT of the brain (10 and 10), MR studies (1 premortem and 1 postmortem), and autopsy findings in 11 AIDS patients with CNS cryptococcosis were reviewed. The imaging studies and pathological specimens were analyzed for signs of meningitis, presence of dilated Virchow-Robin spaces, gelatinous pseudocysts, cryptococcoma, ventriculomegaly, choroid plexus, and ependymal lesions.

RESULTS: Five of 11 patients were found at autopsy to have macroscopically visible "cystic" lesions in the dentate nuclei that were not detected on CT (10 patients), but were seen on premortem MR (1 patient). Macroscopic supratentorial (basal ganglia, thalamic, midbrain) lesions were detected by CT in 5 of 11 patients and by MR in 2 of 2 patients. Enhancement of the leptomeninges was seen in only 1 patient by CT despite pathological evidence of cryptococcal meningitis in all 11 patients. Dilated Virchow-Robin spaces were seen in all 11 pathologic specimens and in the 2 MR studies but not on CT. Communicating hydrocephalus was detected by CT in two patients.

CONCLUSION: CT scans of the brain underestimate infratentorial parenchymal cryptococcal disease. MR is a more sensitive procedure to evaluate cerebellar and brainstem cryptococcosis, including the dentate nuclei, which in our autopsy series was not an uncommon site to be infected with cryptococcal gelatinous pseudocysts.