Table 2.
Summary of immunophenotypic and molecular features of pilocytic astrocytomas with anaplasia (PA‐A)
| Alteration | PA‐A | PA precursor |
|---|---|---|
| ALT | 25/36 (69%) | 9/14 |
| ATRX (IHC) loss | 20/35 (57%) | 7/11 |
| IDH1 (R132H) | 0/32 (0%) | NA |
| BRAF duplication | 8/26 (31%) | 8/14 |
| BRAF (V600E) | 0/31 (0%) * | NA |
| NF1 status | 12/36 (33%) † | 3/19 |
| H3‐K27M | 5/32 (16%) | 2/14 |
| CDKN2A | 3/18 (17%) ‡ | NA |
| P53 (strong IHC) | 6/17 (35%) | NA |
ALT = alternative lengthening of telomeres, NF1 = neurofibromatosis type 1.
*
A single case had an activating mutation in BRAF (non V600E) by sequencing (BRAF p.D594G).
†
A total of 8 patients satisfied clinical criteria for NF1 while four additional patients demonstrated NF1 mutations in their tumors by sequencing studies.
‡
A total of 3 patients had homozygous deletion as tested by FISH (n = 12), NGS (n = 6), or both (n = 1).