Presentation
5 months headaches and visual changes, following a febrile illness while overseas. Previously well.
Patient Data
The patient went on to have a stereotactic biopsy from the frontal lobe.
Histology
Paraffin sections show cores of cerebral white matter. These show prominent perivascular cuffs of small lymphoid cells which are a mixture of CD3+ T lymphocytes and CD20+ B lymphocytes. Smaller numbers of CD68+ monocyte-macrophages are also present in these perivascular aggregates. Vessel walls are intact. There is expansion of perivascular spaces. In one of the cores in specimen 2 there is a well-demarcated area of demyelination. Many monocyte-macrophages containing cytoplasmic myelin debris are seen in this area. There is activation of microglial cells. The overall features strongly favor inflammatory demyelination. Immunostaining for SV-40/JC/BKV is negative. No organisms are identified and there is no evidence of tumor.
DIAGNOSIS:
Stereotactic brain biopsies: Features strongly suggestive of inflammatory demyelination; no evidence of tumor seen.
Clinical progress
The patient was treated with 3 x methyl prednisolone for the diagnosis of ADEM. Clinically had a relapsing / remitting symptoms with two additional MRI scans (2 and 3 months later) demonstrating relatively stable features, but continued enhancement of the occipital lesion. Increasing headaches and confusion prompted a further MRI scan.
The periventricular burden of FLAIR signal abnormality has progressed. The left frontal biopsy tract is noted with residual hemosiderin 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. The MR spectroscopy trace demonstrates a marked elevation in choline and lactate peak.
The remainder of the brain is within normal limits, with no intra or extraaxial collection, mass or region of abnormal contrast enhancement.
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.
The patient went on to have a biopsy of the occipital lobe.
MICROSCOPIC DESCRIPTION:
Paraffin sections show a densely hypercellular tumor. Tumor 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. Tumor 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.
EBER-CISH is NEGATIVE
DIAGNOSIS: non Hodgkin diffuse large B cell lymphoma.
Case Discussion
The diagnosis of lymphoma is not always straight forward, and in this case it remains difficult to know whether the two processes were coincidental or more likely related to each other. Demyelination preceding a CNS lymphoma is a recognized phenomenon, and is likely the case in this instance.
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