Cryptococcal choroid plexitis as a mass lesion: MR imaging and histopathologic correlation

Abstract

Cryptococcosis is a relatively common mycotic infection of the CNS caused by a ubiquitous saprophytic fungus. We present an unusual case of CNS cryptococcosis in an immunocompetent patient. Florid choroid plexitis resulted in the formation of intraventricular enhancing mass lesions that filled the ventricles and were hyperintense to associated periventricular edema on T2-weighted MR images. We also noted lesions corresponding to microcystic, dilated Virchow-Robin spaces in the basal ganglia that were characteristic of cryptococcal infection.

Fig 1.

Brain MR imaging in a 44-year-old man. A, Axial T1-weighted MR image (672/14 [TR/TE]) depicts a hypointense multicystic mass lesion (arrow) in the left temporal horn; the temporal horn is trapped. Periventricular white matter is also hypointense, and the right medial temporal lobe shows a single rounded lesion (arrowhead) with similar features. B, Axial T2-weighted (5500/90) image depicts the mass lesion (arrow) in the temporal lobe, periventricular white matter, and the single rounded lesion (arrowhead) in the right medial temporal lobe as hyperintense. C, Axial T1-weighted (672/14) image reveals an enhancing mass in the region of the foramen of Monro (arrowheads), extending bilaterally into the frontal horns. Choroid plexuses are enlarged and enhanced (arrow). D, Coronal T1-weighted (672/14) image shows enhancement of the meninges (arrow). E, Axial fluid-attenuated inversion recovery (9000/119) image reveals dilated hyperintense Virchow-Robin spaces (arrow) in the basal ganglia.

Fig 2.

Examination of the brain 5 hours after death. A, Coronal section of the brain through mammillary bodies shows a mass filling the superior part of the anterior third ventricle, totally blocking both foramina of Munro, and a similar mass plugging the left temporal horn. B, Whole-mount section through the third ventricle shows a multicystic, pale mass of cryptococci adhering to the corpus callosum (C) and obliterating the foramina of Munro (arrowheads). Note the ragged ventricular lining. Myelin stain, magnification ×3. C, Whole-mount section through the left temporal horn shows a multicystic cryptococcal mass filling the left temporal horn, sparing only a small area of the ventricle (V). The surrounding white matter is pale because of edema and demyelination. Myelin stain, magnification ×2.

Fig 3.

Microphotograph showing cryptococci (arrowheads) floating in a mucoid background in the Virchow Robin space surrounding a vessel (V). Hematoxylin-eosin stain, magnification ×300.