Presentation
Increasing difficulty mobilizing and confusion.
Patient Data
Right insular mass is hyperdense with moderate contrast enhancement and surrounding edema with mass effect.
Enhancing mass in the right frontal lobe, is, on pre-contrast T1/T2, mildly hypointense to gray matter with an area of central fluid signal. The solid component demonstrates several regions of low ADC signal with restricted diffusion noted anteriorly corresponding to a small satellite focus of nodular enhancement. Further separate linear focus of enhancement medially adjacent to the right caudate head/anterior limb internal capsule. Extensive surrounding high FLAIR/T2 signal extending into right cerebral peduncle/midbrain. Resultant positive mass effect with right lateral ventricle partial effacement and midline shift of 5 mm to the left. No hydrocephalus. Small foci of susceptibility artifact, which on phase imaging represent tiny focal hemorrhages. MR spectroscopy demonstrates elevated lactate peak, decreased NAA peak, and reversal of the choline to creatine ratio. The mass demonstrates low CBV compared to the adjacent abnormal white matter.
Conclusion:
Findings are most in keeping with lymphoma.
Post contrast T1 volumetric acquisition through the brain for the purposes of stereotaxis has been obtained. Please refer to previous diagnostic studies for futher details. The enhancing portion of the right insular mass appears significantly smaller than previous MRI consistent with treatment with steroids, and supporting the diagnosis of CNS lymphoma.
Case Discussion
The patient went on to have surgery.
Histology
MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of white matter in which there is edema and reactive astrocytic gliosis. No evidence of tumor is seen. Paraffin sections show fragments of densely hypercellular tissue. These are composed of diffuse sheets of cells with large vesicular nuclei, many with conspicuous sometimes multiple nucleoli and a narrow rim of pale cytoplasm. Frequent mitotic and apoptotic figures are noted and there are scattered small foci of necrosis.
Immunohistochemistry results show tumor cells stain: CD10+, CD20+, BCL2+, BCL6+, MUM1+, CD30- and EBER-CISH-. The CD3 and CD5 stains highlight background T-cells. The features are of those of diffuse large B cell lymphoma, consistent with a germinal center immunophenotype.
FINAL DIAGNOSIS: Brain tissue insula: White matter with reactive changes only; no evidence tumor seen. Brain tissue insula: Diffuse large B cell lymphoma, germinal center type.
Discussion
This example illustrates not only fairly typical appearances of CNS lymphoma, but also the response to steroid.
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