PMC6481150_01
(a) Coronal T1 flair, postcontrast imaging 2 months prior to admission. No enhancing lesion seen. (b) Sagittal T1 flair, postcontrast imaging 2 months prior to admission. No enhancing lesion seen. (c) Coronal T1 flair, postcontrast imaging. There is a 1.7 x 2.5 x 1.8 cm homogenously enhancing mass with mild perilesional edema. (d) Sagittal T1 flair, postcontrast imaging. There is a 1.7 x 2.5 x 1.8 cm homogenously enhancing mass arising from the roof of the 4th ventricle invading into the cerebellar vermis.
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The patient underwent an MRI and magnetic resonance venography (MRV) upon seizure onset that revealed 2 areas of chronic hemorrhage but was otherwise unremarkable (Figure 1). An MRI showed a 2.5 x 1.8 x 1.7 cm homogenously enhancing mass that extended from the roof of the 4th ventricle (Figure 1).
Primary CNS lymphoma arising from the 4th ventricle. (a) Diffuse sheets of lymphoid tumor cells with focal necrosis, H&E stain, 40x magnification. (b) Large atypical tumor cells with angiocentric localization, H&E stain, 400x magnification. (c) CD20 immunostain, 400x magnification. (d) BCL-6 immunostain, 400x magnification. (e) MUM-1 immunostain, 400x magnification. (f) Ki-67 (MIB-1) immunostain (80% proliferation index), 400x magnification.
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Permanent sections confirmed the findings and highlighted the diffuse and angiocentric nature of the lymphoma, which was comprised primarily of large-sized lymphoma cells (Figure 2).
PET imaging of the brain showing increased uptake in the pituitary (a) and the posterior fossa (b). PET: positron emission tomography.
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Positron emission tomography (PET) indicated increased uptake (SUV of 19.3) in the 4th ventricular mass as well as a small focus of uptake in the right pituitary gland (Figure 3).