Pleomorphic xanthoastrocytoma

Case contributed by Dr Bruno Di Muzio

Presentation

First seizure.

Patient Data

Age: 21-year-old

CT Brain

Modality: CT

Ventricular size and sulcal pattern within normal limits. No intra or extra-axial haemorrhage identified. There is a tiny hypoattenuating nodule in the right temporal lobe, at the region of the Heschl's gyrus. Grey-white matter differentiation is preserved with no midline shift. The posterior fossa has a normal appearance. Visualised paranasal sinuses and mastoid air cells are clear.

MRI Brain

Modality: MRI

Small cystic foci measuring 4 and 2 mm respectively are seen involving cortex and subcortical region of the right Heschl's gyrus. These areas do not fully FLAIR suppress. On the FLAIR sequence, there is a poor definition of the adjacent grey matter with mild regional FLAIR hyperintensity. Mild mass effect. Several punctate foci of FLAIR hyperintensity in the supratentorial white matter are non-specific, but borderline prominent for age. History of migraines? No other focal lesion is identified. 

MRI Brain (4 months later)

Modality: MRI

On this study, a single cystic lesion is noted. The second lesion is probably present but not clearly seen as it is smaller than the 5 mm thick slices. High-resolution thinner slices are performed on the post contrast imaging which demonstrates an area of increased enhancement at Heschl's gyrus with mild probable ring enhancement of the cystic lesion. No other definite abnormal contrast enhancement is seen. The ventricles and CSF spaces are within normal limits. No other focal lesions are present. No blood degradation products or diffusion restriction is apparent. 

Modality: Pathology

MICROSCOPIC DESCRIPTION: 1-2. Sections show fragments of a hypercellular tumour composed of cells demonstrating moderate nuclear pleomorphism. Focally tumour cells show an elongate, plump spindle cell morphology with a fascicular arrangement. Large pleomorphic tumour cells with foamy cytoplasm and multinucleated floret cells are present. Eosinophilic granular bodies and aggregates of perivascular lymphocytes are identified. No neuronal tumour cell component is seen. Occasional mitotic figures are identified (up to 3 per 50hpf). No microvascular proliferation or pallisaded tumour necrosis are seen.

Immunohistochemistry results show tumour cells stain:

  • GFAP Positive
  • Nestin Positive
  • NogoA Negative
  • IDH-1 R132H Negative (not mutated)
  • ATRX Positive (not mutated)
  • MGMT Positive (likely not methylated)
  • p53 Positive
  • p16 CDKN2A Positive
  • B-tubulin Positive
  • Topoisomerase labelling index: Approximately 8%. 

DIAGNOSIS: 1-2. Brain tissue: Pleomorphic Xanthoastrocytoma (WHO Grade II).

Case Discussion

Pleomorphic xanthoastrocytomas (PXA) are a type of rare, low-grade astrocytoma (WHO Grade II) found in young patients who typically present with temporal lobe epilepsy, as in this case. 

They are commonly characterised as cortical tumours with a cystic component and vivid contrast enhancement. Differentials would include ganglioglioma (can look very similar) and dysembryoplastic neuroepithelial tumours (DNET).

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Case Information

rID: 46149
Case created: 23rd Jun 2016
Last edited: 23rd Jun 2016
Inclusion in quiz mode: Included

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