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)