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Washington University Experience | NEOPLASMS (GLIAL) | Astrocytoma, IDH-mutant, WHO Grade 2 | 12D (Case 12) Ki67 20X
Ki-67 (MIB-1 antibody) highlights a proliferation index of up to 2.3%. ---- Not shown: P53 immunoreactivity is found in a large subset of tumor cells consistent with a 'mutant staining pattern'. FISH shows polysomy of chromosome 9, with no evidence of CDKN2A deletion and no evidence of 1p/19q deletion. NGS (FoundationOne) shows mutations in IDH, TP53 and ATRX. There is no evidence of homozygous CDKN2A deletion by sequencing nor is there evidence of CIC, FUBP1 and Tert promotor mutations. ---- Comment: The collective findings support the "integrated” diagnosis of: "Astrocytoma, IDH1 (R132H) mutant by immunohistochemistry, WHO grade 2" that is clinically residual/recurrent. Of note, the terminology and grading criteria utilized in this diagnosis is in concordance with a recent c-IMPACT NOW update on IDH-mutant astrocytomas (PMID:31996992).
