Oligodendroglioma (IDH-mt, 1p19q codeleted)

Case contributed by Dr Bruno Di Muzio

Presentation

Presentation with first seizure. Normal neurological examination. Past history of bladder cancer.

Patient Data

Age: 50-year-old

CT Brain

Modality: CT

In the left posterior part of the superior frontal gyrus, extending medially to involve the anterosuperior part of the paracentral lobule, there is a region of hypoattenuation with the involvement of the overlying cortex and positive mass effect. There is associated low attenuation in the white matter extending into the precentral gyrus (oedema/tumour spread). On postcontrast imaging, no abnormal enhancement is demonstrated. The remainder of the brain is unremarkable in appearance. Ventricles are within normal limits in size. No focal osseous lesion. Small subcutaneous nodule is demonstrated beneath the left parietal scalp, most likely representing a sebaceous cyst/epidermal cyst. 

MRI Brain

Modality: MRI

Correlating to the low density on CT brain, centred at the posterior-most aspect of the left superior frontal gyrus, is a moderate-sized area of FLAIR intensity involving and expanding cortex and with local mass-effect. The abnormal signal extends posteriorly to the precentral gyrus mainly medial to the hand knob. They are small foci of FLAIR hypointensity in and no definite enhancement. Only small area of mild diffusion restriction is present. MRS demonstrates mild reversal of the choline-creatine peak and mildly reduced NAA. No increased CBV. No susceptibility. Equivocal overlying bony remodelling. Paranasal sinus mucosal disease. 

Modality: Pathology

MICROSCOPIC DESCRIPTION:

Sections show a moderately cellular tumour composed of cells containing round to oval, hyperchromatic, vesicular nuclei with inconspicuous nucleoli and prominent perinuclear clearing. Tumour cells are arranged in diffuse sheets intersected by thin-walled "chicken-wire" capillaries. Secondary structuring with perineuronal satellitosis and subpial condensation are noted. Focal microcystic change is seen. No calcifications are seen. Occasional mitotic figures are identified (up to 2/10hpf). No necrosis or microvascular proliferation is seen. 

IMMUNOHISTOCHEMISTRY: GFAP Positive Nogo A Positive Nestin Positive (intermediate) IDH-1 R132H Positive (mutated) ATRX Positive (non-mutated) MGMT Negative (likely methylated) p53 Negative p16 Positive Topoisomerase labelling index: 10%. 

FISH for chromosome 1p/19q deletion. 

1p36 DELETION DETECTED 19q13.3 DELETION DETECTED 

  • Number of cells scored 200 
  • Number of sites scored 10
  • 1p36/1q25 ratio 0.69 
  • 19q13.3/19p13 ratio 0.58 

REFERENCE CRITERIA: 

  • 1p36/1q25 ratio <0.8 Deletion detected 
  • 19q13.3/19p23 ratio <0.8 Deletion detected 

FINAL DIAGNOSIS: Oligodendroglioma, IDH-mutated, 1p/19q co-deleted (WHO Grade II)

Case Discussion

This case illustrates a low-grade oligodendroglioma satisfying the new WHO criteria for diagnosis. 

  • IDH-mutant = IDH positive = mutation present = better prognosis
  • 1p/19q co-deleted = relevant marker of longer overall survival in patients with low-grade gliomas

This is a WHO Grade II tumour. 

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Case Information

rID: 48852
Case created: 27th Oct 2016
Last edited: 20th May 2017
Inclusion in quiz mode: Included

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