Presentation
Increasing headaches.
Patient Data
There is extensive vasogenic edema in the posterior right frontal and parietal lobe noted, centered on a hypodense mass with peripheral rim enhancement. There is, in addition, an associated more solid enhancing nodule in the lateral sidewall. There is leftward midline shift. The fourth ventricle and basal cisterns are not effaced.
CONCLUSION: Large cystic and solid mass lesion in the right frontal lobe as described above. This is atypical for an abscess and is likely neoplastic in nature.
Intraaxial lesion is predominantly T2 hyperintense and incompletely FLAIR suppressing with an irregular enhancing nodular mural component, thin enhancing internal septa and peripheral rim enhancement. No diffusion restriction. Minor speckled internal susceptibility artefact within the nodular component, in keeping with previous microhemorrhage. Adjacent T2/FLAIR white matter hyperintensity, extending slightly into the body of the corpus callosum. Associated mass effect with local sulcal effacement, partial effacement of the right lateral ventricle and midline shift to the left. MR spectroscopy is non-contributory. Increased cerebral blood flow and volume in the enhancing components. No other lesion identified.
Conclusion: Mixed solid-cystic appearing right frontoparietal lesion most likely representing a high-grade glioma.
The patient went on to have a resection.
The sections show a cellular pleomorphic tumor. The tumor is highly cellular with large irregular pleomorphic cells. Some of the cells show marked nuclear pleomorphism and nuclear irregularity. Prominent mitotic figures are seen with some abnormal mitotic figure forms. Areas of vascular proliferation are identified and also other areas which show necrosis.
Immunohistochemistry:
- GFAP - positive
- IDH-1 R132H negative (not mutated)
- ATRX - positive (not mutated)
- p53 - <10% (negative)
- p16 CDKN2A - negative
- topoisomerase- 20%
DIAGNOSIS: glioblastoma. WHO grade 4. Features favor IDH wild type. Due to the young age of the patient, molecular testing will be requested (subsequently shown to be wild-type).
Right parietal craniotomy with subjacent expected post surgical change. Parietal lobe resection cavity. Rim enhancement of the resection cavity with slightly increased CBV. The extent of surrounding high T2 and FLAIR signal is significantly increased compared to previous with non-enhancing tumor now extending across the midline at the posterior aspect of the corpus callosum. MR spectroscopy (not shown) continues to demonstrate significant elevation of choline. Multiple bilateral punctate subcortical white matter hyperintensities compatible with background chronic small vessel ischemia.
Conclusion: The appearance is consistent with tumor progression.
Although the degree of enhancement surrounding the resection cavity has substantially reduced as has the amount of vasogenic edema, new small foci of nodular enhancement is identified superomedial to the resection cavity within a mass of the non-enhancing tumor. ADC value within the lesion measures up to 920 x 10^-6 mm^2/s in keeping with fairly high cellularity. MR perfusion demonstrates some increase in cerebral blood volume. MR spectroscopy (not shown) demonstrates elevated choline as previous.
Conclusion: Prominent largely non-enhancing tumor growth superiorly despite reduction in enhancement and edema are in keeping with pseudoresponse (due to Avastin) and progression.
Case Discussion
Care must be taken when interpreting studies in patients who are on Avastin as it has a powerful anti-enhancement and anti-edema effect. The combination can result in apparent tumor regression (known as pseudoresponse) when in fact the tumor may be stable or, as in this case, actually grown.
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