Tumefactive demyelination

Case contributed by Dr Andrew Lawson

Presentation

Blurry vision in right eye in 2012. Then well until 2013, when she developed left homonymous hemianopia.

Patient Data

Age: 52
Gender: Female
MRI

High T2 signal around right optic nerve, at first presentation.

CT

One year later, large, non enhancing lesion in right occipital lobe.

MRI

Since the previous investigation, there has been significant progressive FLAIR signal change extending into the left posterior parietal and occipital lobes. There is avid, nodular enhancement along the peripheral margin of the FLAIR signal abnormality both in the parietal and occipital lobes. The enhancement pattern is distinctly limited to the typical 'advancing front' of active demyelinating plaque. The enhancing nodularity demonstrates restricted diffusion. Previous right occipital biopsy site noted. The volume of FLAIR signal abnormality related to the posterior right parietal and occipital lobes has substantially reduced. The small region of nodular enhancement visible in the more anterior component of the FLAIR signal abnormality has completely resolved. T2 signal abnormality in the tail of the corpus callosum remains visible. The remainder of the brain is within normal limits, with no intra or extraaxial collection, mass or region of abnormal contrast enhancement.

Conclusion: 1. There has been interval progression of the FLAIR signal abnormality in the left parietal and occipital lobes with an avidly enhancing peripheral margin consistent with active tumefactive demyelination. 2. No residual enhancement demonstrated in the right parieto-occipital region.

MRI

There is a large region of FLAIR/T2 hyperintensity within the right parieto- occipital lobe measuring approximately 42 x 35 mm in diameter. The more anteromedial component of the T2 signal change extends into the spenium of the corpus callosum and crosses the midline. Ill-defined peripheral nodular enhancement is demonstrated along the margins of the lesion with no enhancing component demonstrated across the corpus callosum. The MR spectroscopy trace reveals elevated choline peaks and depressed NAA peaks. There are large lipid/lactate peaks. There is reduction in the regional perfusion. Restricted diffusion is shown only in the very peripheral portion of the lesion. Minimal mass effect is exerted on the adjacent parenchyma. The midline remains central. There is a region of focal T2 hyperintensity measuring approximately 8 mm within the central pons. This region does not return FLAIR high signal or demonstrate contrast enhancement. The remainder of the imaged brain is unremarkable.

Conclusion: The imaging features are consistent with a glial series tumour. Presence of a large lipid/lactate peak suggest the presence of necrosis. Together with the presence of ill-defined enhancement it suggests at least WHO 3, probably WHO 4. The absence of elevated relative cerebral blood volume (CBV) would be unusual for this diagnosis. Tumefactive multiple sclerosis could satisfy most of the diagnostic features, in which case the pontine lesion may also be demyelination.

Points to consider:

There was a T2 bright lesion in the pons - was it a second tumour or part of the demyelination?

No glutamate peaks on the MRS

No elevation of CBV, unusual for tumour.

Initial history of optic neuritis not available.

Pathology

See path report.

Case Discussion

Pathology report:

Paraffin sections show small fragments of cerebral cortex and white matter. The cortex appears unremarkable. Luxol Fast Blue staining shows several areas with reduced myelin density which are sharply demarcated from adjacent white matter with intact myelin. Within these demyelinated areas there are large numbers of CD68+ monocyte-macrophages with strong surface expression of MHC Class II. Granular LFB+ myelin debris is noted within the cytoplasm of these cells. Activation of microglia with strong MHC Class II expression is also noted. Small calibre blood vessels are surrounded by narrow cuffs of T lymphocytes (CD4>CD8). No viral inclusion bodies are identified. There is no evidence of tumour. The features are of inflammatory demyelination.

DIAGNOSIS:  "Brain biopsies": Inflammatory demyelination.

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Case information

rID: 25267
Case created: 16th Oct 2013
Last edited: 5th Feb 2016
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