TABLE 2.
Clinicopathologic and Molecular Features of Pediatric Oligodendrogliomas
| N (%) | ||
|---|---|---|
| Grade II Oligodendroglioma (N=38) | Grade III Oligodendroglioma (N=12) | |
| Round nuclei | 38 (100) | 12 (100) |
| Perinuclear halos | 38 (100) | 12 (100) |
| Microcysts | 14 (44) | 4 (40) |
| Microcalcifications | 15 (48) | 4 (40) |
| Secondary structures | 3 (91) | 6 (75) |
| Leptomeningeal extension | 3 (10) | 0 |
| Nodular architecture | 2 (6) | 1 (10) |
| Cortical involvement | 27 (90) | 6 (60) |
| Minigemistocytes | 3 (9) | 1 (10) |
| Gliofibrillary oligodendrocytes | 0 | 1 (10) |
| Microvascular changes | 1 (3) | 7 (70) |
| Necrosis | 1 (3) | 3 (30) |
| GFAP expression | ||
| Positive | 1 (17) | 0 |
| Focal | 2 (33) | 0 |
| S100 expression | ||
| Positive | 3 (100) | NA |
| Synaptophysin expression | ||
| Positive | 1 (13) | 1 (17) |
| Strong p53 immunostaining | 0 | 1 (14) |
| IDH1 (R132H) | ||
| Positive | 3 (19) | 1 (17) |
| 1p19q | ||
| Codeletion | 6 (21) | 4 (36) |
| 1p loss only | 0 | 1 (9) |
| 1p19q intact | 23 (79) | 6 (55) |