Tumour mimicking demyelination

Case contributed by Dr Andrew Lawson

Presentation

5 months headaches, dysphasia, some visual loss.

Patient Data

Age: 35
Gender: Female
MRI

Multiple bilateral ovoid, periventricular and callososeptal T2 hyperintense, T1 hypointense lesions are demonstrated. The lesions are perpendicularly orientated to the ventricles. A right frontal juxtacortical lesion is also seen. There is moderate surrounding adjacent FLAIR / T2 high signal. Some of these are T1 hypointense. Several, however not all of these lesions demonstrate contrast enhancement.

A moderate to large area of right parietal cortical abnormality is seen, with oedema / T2 high signal and associated vasogenic oedema involving cortex and underlying white matter. There is vivid contrast enhancement within this region along with diffusion restriction (correspondingly low on ADC map) that mainly involves cortex. There is minimal mass effect for the degree of signal abnormality. No hemorrhage on EPI. No venous sinus thrombosis seen in non dedicated imaging.  No increase in cerebral blood volume.

Conclusion: Overall MRI finding favour demyelination with a tumefactive plaque in the right parietal region and multiple smaller active plaques elsewhere-- particularly consider ADEM or MS variants (such as Marburg's). (Angiocentric) malignancy or cerebral vasculitis are differentials.

MRI

The periventricular burden of FLAIR signal abnormality has progressed. The left frontal biopsy tract is noted with residual haemosiderin staining evident. The periventricular enhancement is again demonstrated and largely stable. The right occipital lesion has shown a discrete change in morphological appearance with increasing mass effect and prominent thickening of the occipital cortex. The surrounding FLAIR signal abnormality remains largely unchanged, however the gyriform pattern of enhancement is far more intense. Extensive restricted diffusion.

Conclusion: The evolution of the right occipital lesion is difficult to reconcile with demyelination, or evolving infarction and an alternative diagnosis should be sought. The possibility of all these changes representing CNS lymphoma should be entertained.

Case Discussion

First biopsy of the left frontal lesions showed demyelination.

Repeat biopsy 4 months later:

Paraffin sections show a densely hypercellular tumour. Tumour cells have features of atypical large lymphoid cells with large round and oval vesicular nuclei many with conspicuous nucleoli and a narrow rim of pale cytoplasm. These are arranged in diffuse sheets in a vascular stroma. Frequent mitotic figures and apoptoses are identified. Tumour appears to completely replace brain parenchyma. IMMUNOHISTOCHEMISTRY: Atypical lymphoid cells show strong membrane staining for CD20, strong nuclear staining for bcl-6 and MUM-1 and strong perinuclear staining for bcl-2. Moderate numbers of small CD3+ T lymphocytes are scattered among the large atypical cells. No staining for CD5, CD23 or cyclin D1 is seen in the large atypical cels.

The features are of non Hodgkin lymphoma - diffuse large B cell type.

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Case information

rID: 26098
Case created: 29th Nov 2013
Last edited: 29th Sep 2015
Inclusion in quiz mode: Included

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