Astroblastoma

Case contributed by Prof Alan Coulthard

Presentation

Presented with two episodes of tonic-clonic seizures and headache.

Patient Data

Age: 25 years
Gender: Female
CT

There is a small heterogenous predominantly hyperdense mass in the right parietal lobe, with precessional hypodensity suggesting oedema. No calcifications were noted on bone window images (not shown).

MRI

Mass lesion predominantly T1 isointense to white matter, with focal hypointense areas. Adjacent white matter T1 hypointensity.

On T2 there are areas of marked hypointensity and small areas of hyperintensity, with marked vasogenic oedema. The lesion appears cortically-based, and is heterogeneous on FLAIR, with foci of marked hypointensity.

b1000 images suggest some marginal diffusion restriction. ADC confirms some minimal marginal diffusion restriction.

Postcontrast images show prominent enhancement, with a few small areas of non-enhancement. The enhanced lesion is well defined.

MRI

Post contrast MRI 18 months post excision

Contrast-enhanced T1 MRI acquired 18 months post excision shows a small area of encephalomalacia at the operative site, but no evidence of residual or recurrent tumour.

Case Discussion

The combination of a hyperdense lesion on CT and an avidly enhancing lesion on MRI is often seen in lymphoma, however, typically there is fairly marked diffusion restriction within the lesion, not seen here. The moderate edge restriction was not thought typical of lymphoma. The imaging appearance in conjunction with the prominent vasogenic oedema raised the possibility of a metastasis. Given the age of the patient metastatic melanoma was suggested in the differential. 

At histology, the morphology and immunophenotype were felt to be consistent with an astroblastoma. The histological features were considered low grade (no WHO grading currently exists for these lesions) with a favourable prognosis. Follow up 18 months post surgery shows no residual lesion. 

Astroblastoma is an uncommon glial neoplasm (0.45-2.8% brain gliomas) which is almost always supratentorial, occurring most commonly in young adults. The figure of 85% of lesions showing calcification on CT quoted in the literature is based on a series of 7 patients. No overt calcification was seen on CT in this case, although the lesion was hyperdense. The lesion, in this case, was predominantly isointense, with heterogeneous features in keeping with the reported solid and cystic components in this pathology.

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Case information

rID: 39792
Published: 21st Sep 2015
Last edited: 29th May 2018
Inclusion in quiz mode: Included

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