Zepeda‐Mendoza, Cinthya

Abstract Circumscribed meningeal melanocytic neoplasms (CMMNs) represent a spectrum of rare central nervous system (CNS) tumors. Knowledge of their clinical behavior and molecular correlates remains limited. In this single‐institution retrospective study, we analyzed 31 patients (14 male, 17 female; median age, 59 years) diagnosed with CMMN between 2004 and 2025. In this patient cohort, based on the current World Health Organization Central Nervous System Tumor Classification (WHO CNS5) criteria, the majority of cases (18, 58.1%) fell into the intermediate‐grade melanocytic tumor (IMT) category based on histology, with either increased mitotic activity, CNS invasion, or both; 7 (22.6%) were melanocytomas, 5 (16.1%) melanomas, and 1 (3.2%) indeterminate case because of limited tissue. By next‐generation sequencing, mutations were identified in GNAQ/GNA11 in 21/24 cases, BAP1 in 5/23 (2 IMT, 3 melanoma), EIF1AX in 9/21 (1 melanocytoma, 8 IMT), and SF3B1 in 3/23 (2 IMT, 1 melanoma). Primary sites were spinal (20), posterior fossa (6), and supratentorial (5). During follow‐up, progression was observed in 5/6 melanocytomas, 9/13 IMTs, and 4/5 melanomas, suggesting a high frequency of progression across all groups. Two‐year progression‐free survival was 83.3% (95% confidence interval [CI], 53.5%–100.0%) for melanocytoma, 55.9% (95% CI, 26.7%–85.2%) for IMT, and 25.0% (95% CI, 0.0%–67.4%) for melanoma. Five‐year overall survival (OS) was 80.0% (95% CI, 44.9%–100.0%) for melanocytoma, 65.3% (95% CI, 37.0%–93.6%) for IMT, and 0.0% for melanoma. OS was significantly worse in melanoma compared with melanocytoma ( p = 0.002). BAP1 mutation correlated with worse OS (hazard ratio 8.73, p = 0.006). Upfront maximal safe resection appeared to be associated with improved outcomes in selected patients, whereas radiotherapy and systemic therapy did not demonstrate clear additional benefit in this cohort. In summary, our study shows that all CMMNs, irrespective of grade, have a high propensity to recur and melanoma histology and BAP1 mutation are associated with significantly worse OS.

ABSTRACT We examined the prognostic value of routine NGS data in newly diagnosed acute myeloid leukemia (AML) treated with intensive (7 + 3 backbone) induction, specified by AML subtype. A contemporary (2015–2025) series of 545 Mayo Clinic patients (median age 56 years, females 44%) was considered. Median follow‐up was 49 months with 341 (63%) allogeneic hematopoietic stem cell transplantations (AHSCT) recorded. AML subtypes included core‐binding factor (CBF; N = 72; 13%), primary non‐CBF ( N = 403; 74%), post‐myelodysplastic syndromes (MDS) or post‐myelodysplastic/myeloproliferative neoplasms (post‐MDS‐MDS/MPN; N = 28; 5%), post‐MPN ( N = 15; 3%), and therapy‐related (t‐AML; N = 27; 5%). Corresponding complete remission rates, with/without count recovery (CR/CRi), were 89%, 76%, 64%, 27%, and 78% ( p < 0.01) and 5‐year transplant‐censored survival rates 68%, 57%, 21%, 0%, and 55% ( p < 0.01). In multivariable analyses, the prognostic value of specific mutations was mostly limited to primary non‐CBF AML where adverse karyotype (OR 1.9; p = 0.04) predicted inferior and FLT3 ‐ITD (OR 0.4; p < 0.01) or NPM1 MUT / FLT3 WT (OR 0.1; p < 0.01) superior CR/CRi while KRAS MUT (HR 8.8; p < 0.01), TP53 MUT (HR 5.4; p < 0.01), and TET2 MUT (HR 2.3; p = 0.01) predicted inferior and NPM1 MUT / FLT3 WT (HR 0.3; p = 0.01) superior survival. Prognostication in intensively‐treated AML should start with subtype specification and recognition of the limited value of NGS in non‐primary AML. Post‐MPN AML is particularly associated with dismal outcomes and should be prognostically distinguished from post‐MDS‐MDS/MPN AML. In primary non‐CBF AML, in addition to previously established risk factors, the favorable impact of FLT3 ‐ITD on achieving CR/CRi and the unfavorable impact of KRAS MUT and TET2 MUT on transplant‐censored survival were noted and require confirmation from additional studies.

Context.— One objective of the College of American Pathologists/American College of Medical Genetics Cytogenetics Committee is to ensure the accurate detection and clinical interpretation of abnormalities observed by fluorescence in situ hybridization (FISH) analysis when evaluating hematologic neoplasms. Objective.— To report a 20-year performance summary (2005–2024) of FISH challenges focusing on hematologic neoplasms. Design.— A retrospective review was performed from 2005 through 2024 to identify FISH challenges specifically addressing hematologic neoplasms. The overall performance of participants was evaluated to identify potential recurring errors of clinical relevance. Results.— A total of 124 hematologic neoplasm FISH challenges from 2005 to 2024 were provided to participating laboratories, including 45 paper challenges (results and/or images were provided for interpretation purposes), 43 liquid challenges (bone marrow aspirate or peripheral blood), and 36 formalin-fixed paraffin-embedded (FFPE) tissue challenges. Of the 124 challenges, 120 (97%) exceeded the required 80% consensus for grading purposes. Of the 4 failed challenges (3%), 2 (1 liquid, 1 paper) involved the interpretation of atypical FISH signal patterns; 1 (paper) involved the interpretation of FISH signal patterns correlating involvement by myeloid versus lymphoid interphase nuclei; and 1 (liquid) likely involved a specimen processing or handling error that resulted in discordant participant responses. All 36 FFPE tissue challenges exceeded the 80% consensus for grading purposes. Conclusions.— This 20-year retrospective review demonstrates that clinical cytogenomic laboratories have been and continue to be highly proficient in the detection and interpretation of FISH abnormalities associated with hematologic neoplasms.

6588 Background: TET2 is the most frequently mutated gene in chronic myelomonocytic leukemia (CMML) and has been associated with favorable outcome, with recent studies suggesting a more pronounced prognostic impact in the presence of ≥2 TET2 mutations ( Csizmar et al. leukemia 2025;39:2030; Kynning et al. Br J Haematol. 2025 Nov 25. doi: 10.1111/bjh.70264 ). We sought to determine if this particular observation extended to patients with ≥3 TET2 mutations ( TET2 MUT ) and also held true in the context of recently reiterated genetic risk factors. Methods: The current study was conducted under institutional review board approved minimum risk protocols allowing retrospective patient data collection and analysis. Diagnostic criteria were according to the International Consensus Classification (Arber et al. Blood 2022. 140:1200). All statistical analyses were conducted using JMP 18 software. Results: 536 CMML patients who underwent CLIA-approved NGS testing were stratified according to the number of TET2 MUT : 221 (41%) wild-type, 148 (28%) with one, 153 (29%) 2, and 14 (2%) ≥3 TET2 MUT . Co-mutation frequencies with significant differences between one vs. two TET2 MUT included ASXL1 (46% vs. 29%; p<0.01), KRAS (7% vs. 14%; p=0.02) and SETBP1 (5% vs. 0.6%; p=0.02). Phenotypic comparisons revealed preponderance of prognostically favorable traits associated with wild-type TET2 but no significant differences between one vs. two TET2 MUT . In age-adjusted univariate analysis, transplant-censored overall survival (TCOS), calculated from the time of mutation detection, was superior in patients with one (p<0.01; HR 0.7) or 2 (p<0.01; HR 0.4) but not ≥3 (p=0.4) TET2 MUT , vs. those with wild-type TET2 . TCOS was also superior with 2 vs. 1 (p=0.02; HR 0.7) but not with ≥3 vs. 1 (p=0.7) TET2 MUT ; the results were similar when TCOS was calculated from the time of diagnosis. Multivariable analysis confirmed the survival advantage of exactly two TET2 MUT vs. wild-type TET2 (p<0.01; HR 0.5), one TET2 MUT (p<0.01; HR 0.6), or ≥3 TET2 MUT (p<0.01; HR 0.4), after adjusting for age, sex, anemia, circulating blasts ≥2%, and leukocyte count ≥13×10⁹/L. The favorable impact of exactly two TET2 MUT persisted in CMML-MD and CMML-MP and remained independent of TET2 VAF, mutation type, karyotype, and other prognostically relevant mutations. This association was sustained in the BLAST (p<0.01; HR 0.5) and CPSS-mol (p=0.02; HR 0.7) models, but not in BLAST-mol model (p=0.12). Conclusions: Mechanistic explanation for this novel observation includes the possibility that TET2 mutational categories based on mutation count reflect distinct biological states rather than having a simple linear effect. The persistence of this signal despite adjustment for established molecular and genetic risk factors supports its consideration in the development of future CMML prognostic models.

Background: Acute myeloid leukemia (AML) with CBFB::MYH11 fusion and myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK) are genetically defined and typically mutually exclusive entities. Case Presentation: We report a unique case of de novo AML harboring two clonal, transcriptionally active class-defining fusions: CBFB::MYH11 and GOLGA4::PDGFRB. A 61-year-old woman presented with leukocytosis with neutrophilia, eosinophilia, and monocytosis; circulating blasts; and a markedly hypercellular marrow. Cytogenetic analysis revealed inv(16)(p13.1q22) and t(3;5)(p21;q32) in all 20 metaphases, and RNA sequencing confirmed expression of both CBFB::MYH11 and GOLGA4::PDGFRB fusions. In addition, an oncogenic WT1 frameshift variant was identified. Hematopathologic findings were largely consistent with AML with CBFB::MYH11 fusion but exhibited features reminiscent of PDGFRB-rearranged MLN-TK. The patient achieved complete remission following the standard 7 + 3 induction chemotherapy regimen for AML with gemtuzumab ozogamicin. Conclusions: This case illustrates the diagnostic challenges posed by concomitant class-defining alterations in hematologic neoplasms and underscores the importance of integrated genomic assessment.

Abstract Diffuse hemispheric glioma, H3 G34‐mutant (DHG‐H3 G34) has been primarily molecularly characterized by methylation profiling and sequencing studies. We describe an integrated histomolecular evaluation including high‐resolution copy number profiling of a series of 60 DHG‐H3 G34 to further our understanding of the spectrum of genetic changes associated with this tumor type. Cases were clinically tested using an 187‐gene mutation and fusion targeted neuro‐oncology next‐generation sequencing panel ( n = 60) and Oncoscan chromosomal microarray ( n = 26) by a single laboratory (2018–2022). A subset of cases had immunohistochemical results for OLIG2 ( n = 42), p53 ( n = 48), and ATRX ( n = 46), and methylation array data ( n = 8). Median age at testing was 21 years (range, 12–50). No significant difference was noted in clinical, histopathological, and mutational profile between pediatric and adult patients. H3‐3A G34 mutations included G34R ( n = 56; 94%), G34V ( n = 3), and a non‐canonical G34E ( n = 1). Concurrent mutations most often involved TP53 ( n = 55; 92%), ATRX ( n = 50; 83%), and PDGFRA ( n = 34; 57%). A reportedly primary tumor was confirmed to be hypermutant and had a PMS2 mutation. A single case also showed an FGFR3::FAM184B fusion. All cases with available chromosomal microarray data had unbalanced genomes, which were often complex (14/26; 54%). The most frequent recurrent copy number abnormalities were losses involving 3q, 4q, 10q, 13q, and 18q, and 17p copy‐neutral loss of heterozygosity (cnLOH) encompassing TP53 . This copy number profile was reminiscent of that seen in Grade 4 IDH‐mutant astrocytomas. Collectively, a TP53 abnormality at copy number (12/26, all cnLOH), sequence (55/60) and protein expression (46/48) level was detected in all 60 cases. In conclusion, integrated high‐resolution copy number and histomolecular analysis expanded the spectrum of genetic changes associated with DHG‐H3 G34, including the presence of universal TP53 abnormalities with frequent cnLOH—a copy number abnormality that has been largely unrecognized—for this new 2021 World Health Organization central nervous system tumor type.

Abstract In adult-type diffuse gliomas CDKN2A and/or CDKN2B (CDKN2A/B) deletions often co-occur with deletion of MTAP, suggesting that MTAP immunohistochemistry (IHC) may be a surrogate marker of CDKN2A/B status. However, the association between CDKN2A/B and MTAP deletion at the genomic level remains unknown. We assessed CDKN2A/B and MTAP deletions by chromosomal microarray in 333 adult-type diffuse gliomas and performed MTAP IHC on a subset (n = 63). CDKN2A/B and MTAP deletions were detected in 216 and 215 cases, respectively, and were concurrent in 99.5% (215/216). While most tumors with CDKN2A/B homozygous deletion (n = 148) showed concurrent MTAP homozygous deletion (108/148; 73.0%), a subset harbored MTAP heterozygous deletion (39/148; 26.4%). By analyzing the size of the chromosomal alterations, we demonstrate that initial large chromosomal 9p losses result in concurrent heterozygous deletion of CDKN2A/B and MTAP whereas smaller “second hit” deletions leading to homozygous CDKN2A/B deletion do not always encompass the MTAP locus. Discordant CDKN2A/B and MTAP tumors affect the association between MTAP IHC and copy number status of MTAP and CDKN2A/B. These findings suggest that adult-type diffuse gliomas, regardless of IDH status, follow a stereotypic pathway involving concurrent CDKN2A/B and MTAP heterozygous deletion but may diverge for CDKN2A/B and MTAP homozygous deletion.