Presentation
Headache, recently much worse.
Patient Data
A sizable mass is seen within the fourth ventricle, isodense to adjacent brain and demonstrating prominent, but not vivid, enhancement. Hydrocephalus is present.
Within the fourth ventricle has an enhancing tumor extending inferiorly posterior to the upper cervical cord. It molds to the contours of the surrounding brainstem and cerebellum. On some of the lower images there appears to be a component arising from the dorsal aspect of the medulla. The mass demonstrates only intermediate diffusion restriction, prominent susceptibility induced signal loss suggesting blood product, without frank hemorrhage.
On the right side of the lesion a more focal region demonstrates signal loss and increased density on CT and may represent calcification or more acute blood. The PICAs are embedded with thin the mass without obvious large additional flow voids. The outlet to the fourth ventricle is occluded with resultant obstructive hydrocephalous and minor transependymal edema. The remainder of the brain is unremarkable in appearance,
Conclusion: Fourth ventricular mass almost certainly represents an ependymoma. Choroid plexus papilloma and hemangioblastoma are much less likely differentials.
Case Discussion
The patient went on to have surgery.
Histology
MICROSCOPIC DESCRIPTION: Sections show a moderately cellular tumor with a fibrillary background forming prominent perivascular pseudorosettes. True rosettes are absent. Tumor cells demonstrate mildly enlarged elongated nuclei and inconspicuous nucleoli. No mitoses are seen. No microvascular proliferation or necrosis is seen.
Immunohistochemically tumor cells stain: GFAP+ and EMA+ (perinuclear dot positivity). The Topoisomerase proliferation index is approximately: 1-2%. .
FINAL DIAGNOSIS: Ependymoma (WHO Grade II).
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