Gliomatosis cerebri - rapidly progressing
A 53-year-old female was referred to the eye clinic by the optician who had performed a visual field that revealed a left hemianopia. The patient had been diagnosed with depression and started on antidepressants by her general practitioner. Following this, she reported feeling unwell and experiencing memory loss, loss of peripheral vision, loss of coordination, intense headaches that were worse in the morning, blurry vision, and pain behind the eyes. A neurological examination was performed but the patient was struggling to follow instructions, and cerebellar signs were present: past finger pointing on both sides, but more evident on the left side, she struggled to perform heel/shin test and had a slight left palmar drift on her left side.
MRI Brain (selected images)
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The MRI revealed an extensive infiltrating glioma with the expansion of the posterior body and splenium of the corpus callosum, involving both medial parietal lobes. The right side is more extensive infiltrating around the lateral ventricle to involve the thalamus, parieto-temporal deep white matter. The left side of the tumour extended into the left medial parietal deep white matter, with a focal area of irregular enhancement and central necrosis, this being suggestive of a high-grade necrotic component.
A second MRI (8 days apart) was suggestive of a very extensive infiltrating glioma or gliomatosis cerebri. With areas of high grade transformation that seem to be progressing very rapidly (new areas of necrosis and enhancement developing in the callosal components, as well as other new areas of restricted diffusivity suggesting higher grade transformation but in the pre-necrotic stage).
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The pathological appearances need to be assessed in conjunction with the neuro
imaging as reported previously
Following imaging findings, the patient underwent a right-sided burr hole biopsy for the space-occupying lesion. A brain biopsy needle was registered and inserted under neuronavigational guidance.
Multiple biopsies were taken (frozen section and paraffin). Histopathological investigation of samples from the right parietal lesion and the right trigone brain lesion was conducted.
Microscopic examination of both specimens reveals the presence of a diffusely infiltrating glioma. Viewed in isolation, the pathology would be consistent with a low-grade glioma, specifically a gemistocytic astrocytoma. Interpreted in conjunction with the neuroimages, available appearances are more consistent with gliomatosis cerebri WHO grade III.
In the differential, some consideration was given to the possibility of bizarre reactive astrocytosis as might be seen with lymphomas that have resolved following steroid treatment. Even relying only on the pathology, though, such a diagnosis is thought extremely unlikely. Assessed in conjunction with the radiological studies, this possibility becomes implausible. The histopathological appearance may, however, be seen in cases of gliomatosis cerebri, and it would appear that the radiology is consistent with such a diagnosis. Although the histological findings on the available material are compatible with that of a low-grade glioma (Grade II), gliomatosis cerebri by definition should be regarded as a tumour with poor prognosis.
Importantly, whereas gliomatosis was previously considered a distinct entity, since the 2016 update to the WHO classification of CNS tumours it is now merely thought of as a growth pattern.