Cytogenetic and pathologic characterization of MYC-rearranged B-cell lymphomas in pediatric and young adult patients

MYC-rearranged B-cell lymphoma (BCL) in the pediatric/young adult (YA) age group differs substantially in disease composition from adult cohorts. However, data regarding the partner genes, concurrent rearrangements, and ultimate diagnoses in these patients is scarce compared to that in adult cohorts. We aimed to characterize the spectrum of MYC-rearranged (MYC-R) mature, aggressive BCL in the pediatric/YA population. A retrospective study of morphologic, immunophenotypic, and fluorescence in situ hybridization (FISH) results of patients age ≤ 30 years with suspected Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL) or high-grade B-cell lymphoma (HGBCL), and a MYC-R by FISH between 2013-2022 was performed. Two-hundred fifty-eight cases (129 (50%) pediatric (< 18 years) and 129 (50%) YA (18-30 years)) were included. Most MYC-R BCL in pediatric (89%) and YA (66%) cases were BL. While double-hit (DH) cytogenetics (MYC with BCL2 and/or BCL6-R, HGBCL-DH) was rare in the pediatric population (2/129, 2%), HGBCL-DH increased with age and was identified in 17/129 (13%) of YA cases. Most HGBCL-DH had MYC and BCL6-R, while BCL2-R were rare in both groups (3/258, 1%). MYC-R without an IG partner was more common in the YA group (14/116 (12%) vs 2/128 (2%), p = 0.001). The pediatric to YA transition is characterized by decreasing frequency in BL and increasing genetic heterogeneity of MYC-R BCL, with emergence of DH-BCL with MYC and BCL6-R. FISH to evaluate for BCL2 and BCL6 rearrangements is likely not warranted in the pediatric population but should continue to be applied in YA BCL.

TP53 variant allele frequency and therapy-related setting independently predict survival in myelodysplastic syndromes with del(5q)

Among 210 patients with myelodysplastic syndromes (MDSs) with del(5q), molecular information was available at diagnosis or at least 3 months before leukaemic transformation in 146 cases. Multivariate analysis identified therapy-related setting (p = 0.02; HR 2.3) and TP53 variant allele frequency (VAF) ≥22% (p < 0.01; HR 2.8), but not SF3B1 mutation (p = 0.65), as independent risk factors for survival. Median survival was 11.7 versus 4 years (5/10-year survival 73%/52% vs. 42%/14%) in the absence (N = 112) versus presence (N = 34) of ≥1 risk factors; leukaemia-free survival was affected by TP53 VAF ≥22% (p < 0.01). Such information might inform treatment decision-making in MDS-del(5q) regarding allogeneic stem cell transplant.

High-grade B-cell lymphoma with a quadruple-hit genetic profile including concurrent MYC, BCL2, BCL6, and CCND1 gene rearrangements

Several reports of concurrent MYC, BCL2, BCL6, and CCND1 rearrangements in high-grade B-cell lymphoma (HGBL) have been recently described. Herein, we aimed to delineate the scope of this entity through a review of HGBL with a "quadruple-hit" genetic profile identified at our institution. We performed a retrospective review (2015-2023) at our institution of B-cell lymphoma (BCL) cases that were evaluated with concurrent MYC, BCL2, and BCL6 break-apart and IGH::MYC and IGH::CCND1 dual-color dual-fusion fluorescence in situ hybridization studies. Of 203 cases meeting inclusion criteria, 2 (1%) with a quadruple-hit genetic profile were identified. Case 1 represented a 59-year-old female with widespread lymphadenopathy and a diagnosis of HGBL who exhibited primary refractoriness to dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (DA-EPOCH-R) chemotherapy. Case 2 represented a 58-year-old male with mediastinal and abdominal lymphadenopathy and a diagnosis of large BCL who died from disease after 1 cycle of DA-EPOCH-R chemotherapy. Similarly, a literature review of 7 previously reported cases of HGBL with a quadruple-hit profile also demonstrated aggressive disease behavior. Our study adds 2 new cases to the rarely encountered quadruple-hit HGBL, and a brief meta-analysis of the 9 available cases indicates aggressive disease behavior conferred by this constellation of genetic events.

Prognostic impact of SF3B1 mutation and multilineage dysplasia in myelodysplastic syndromes with ring sideroblasts: a Mayo Clinic study of 170 informative cases

The revised 4th edition of the World Health Organization (WHO4R) classification lists myelodysplastic syndromes with ring sideroblasts (MDS-RS) as a separate entity with single lineage (MDS-RS-SLD) or multilineage (MDS-RS-MLD) dysplasia. The more recent International Consensus Classification (ICC) distinguishes between MDS with SF3B1 mutation (MDS-SF3B1) and MDS-RS without SF3B1 mutation; the latter is instead included under the category of MDS not otherwise specified. The current study includes 170 Mayo Clinic patients with WHO4R-defined MDS-RS, including MDS-RS-SLD (N=83) and MDS-RS-MLD (N=87); a subset of 145 patients were also evaluable for the presence of SF3B1 and other mutations, including 126 with (87%) and 19 (13%) without SF3B1 mutation. Median overall survival for all 170 patients was 6.6 years with 5- and 10-year survival rates of 59% and 25%, respectively. A significant difference in overall survival was apparent between MDS-RS-MLD and MDS-RS-SLD (p<0.01) but not between MDS-RS with and without SF3B1 mutation (p=0.36). Multivariable analysis confirmed the independent prognostic contribution of MLD (HR 1.8, 95% CI 1.1-2.8; p=0.01) and also identified age (p<0.01), transfusion need at diagnosis (p<0.01), and abnormal karyotype (p<0.01), as additional risk factors; the impact from SF3B1 or other mutations was not significant. Leukemia-free survival was independently affected by abnormal karyotype (p<0.01), RUNX1 (0.02) and IDH1 (p=0.01) mutations, but not by MLD or SF3B1 mutation. Exclusion of patients not meeting ICC-criteria for MDSSF3B1 did not change the observations on overall survival. MLD-based, as opposed to SF3B1 mutationbased, disease classification for MDS-RS might be prognostically more relevant.

One thousand patients with essential thrombocythemia: the Mayo Clinic experience

We describe 1000 patients with essential thrombocythemia seen at the Mayo Clinic between 1967 and 2023: median age 58 years (18-90), females 63%, JAK2/CALR/MPL-mutated 62%/27%/3%, triple-negative (TN) 8%, extreme thrombocytosis (ExT; platelets ≥1000 × 109/L) 26%, leukocytosis (leukocyte count >11 × 109/L) 20%, and abnormal karyotype 6%. JAK2-mutated patients were older (median 71 years), and CALR mutated (52 years), and TN (50 years) younger (p < 0.01). Female gender clustered with TN (73%) and JAK2 (69%) vs. CALR/MPL (49%/47%) mutations (p < 0.01). ExT clustered with CALR (type-2 more than type-1) and TN and leukocytosis with JAK2 mutation (p < 0.01). In multivariable analysis, risk factors for overall survival were older age (p < 0.01), male gender (HR 1.8), absolute neutrophil count (ANC) ≥ 8 × 109/L (HR 1.6), absolute lymphocyte count (ALC) < 1.7 × 109/L (HR 1.5), hypertension (HR 1.7), and arterial thrombosis history (HR 1.7); for leukemia-free survival, ExT (HR 2.3) and abnormal karyotype (HR 3.1); for myelofibrosis-free survival, ANC ≥ 8 × 109/L (HR 2.3) and MPL mutation (HR 3.9); for arterial thrombosis-free survival, age ≥60 years (HR 1.9), male gender (HR 1.6), arterial thrombosis history (HR 1.7), hypertension (HR 1.7), and JAK2 mutation (HR 1.8); for venous thrombosis-free survival, male gender (HR 1.8) and venous thrombosis history (HR 3.0). Associations between ExT and leukemic transformation and between ANC and fibrotic progression were limited to JAK2-mutated cases. Aspirin therapy appeared to mitigate both arterial (HR 0.4) and venous (HR 0.4) thrombosis risk. HR-based risk models delineated patients with median survivals ranging from 10 years to not reached and 20-year leukemia/myelofibrosis incidences from 3%/21% to 12.8%/49%. The current study provides both novel and confirmatory observations of essential thrombocythemia.

Superior detection rate of plasma cell FISH using FACS-FISH

OBJECTIVES

Fluorescence in situ hybridization (FISH) for plasma cell neoplasms (PCNs) requires plasma cell (PC) identification or purification strategies to optimize results. We compared the efficacy of cytoplasmic immunoglobulin FISH (cIg-FISH) and fluorescence-activated cell sorting FISH (FACS-FISH) in a clinical laboratory setting.

METHODS

The FISH analysis results of 14,855 samples from individuals with a suspected PCN subjected to cytogenetic evaluation between 2019 and 2022 with cIg-FISH (n = 6917) or FACS-FISH (n = 7938) testing were analyzed.

RESULTS

Fluorescence-activated cell sorting-FISH increased the detection rate of abnormalities in comparison with cIg-FISH, with abnormal results documented in 54% vs 50% of cases, respectively (P < .001). It improved the detection of IGH::CCND1 (P < .001), IGH::MAF (P < .001), IGH::MAFB (P < .001), other IGH rearrangements (P < .001), and gains/amplifications of 1q (P < .001), whereas the detection rates of IGH::FGFR3 fusions (P = .3), loss of 17p (P = .3), and other abnormalities, including hyperdiploidy (P = .5), were similar. Insufficient PC yield for FISH analysis was decreased between cIg-FISH and FACS-FISH (22% and 3% respectively, P < .001). Flow cytometry allowed establishment of ploidy status in 91% of cases. In addition, FACS-FISH decreased analysis times, workload efforts, and operating costs.

CONCLUSIONS

Fluorescence-activated cell sorting-FISH is an efficient PC purification strategy that affords significant improvement in diagnostic yield and decreases workflow requirements in comparison with cIg-FISH.

A globally applicable "triple A" risk model for essential thrombocythemia based on Age, Absolute neutrophil count, and Absolute lymphocyte count

We examined the individual prognostic contribution of absolute neutrophil (ANC), lymphocyte (ALC), and monocyte (AMC) counts, on overall (OS), leukemia-free (LFS), and myelofibrosis-free (MFFS) survival in essential thrombocythemia (ET). Informative cases (N = 598; median age 59 years; females 62%) were retrospectively accrued from a Mayo Clinic database: JAK2 59%, CALR 27%, triple-negative 11%, and MPL 3%; international prognostic scoring system for ET (IPSET) risk high 21%, intermediate 42%, and low 37%; 7% (37/515) had abnormal karyotype and 10% (21/205) adverse mutations (SF3B1/SRSF2/U2AF1/TP53). At median 8.4 years, 163 (27%) deaths, 71 (12%) fibrotic, and 20 (3%) leukemic transformations were recorded. Multivariable analysis resulted in HR (95% CI) of 16.5 (9.9-27.4) for age > 70 years, 3.7 (2.3-6.0) for age 50-70 years, 2.4 (1.7-3.3) for ANC ≥8 × 109 /L, and 1.9 (1.4-2.6) for ALC <1.7 × 109 /L. The corresponding HR-based scores were 4, 2, 1, and 1, resulting in an new 4-tiered AgeAncAlc (AAA; triple A) risk model: high (5-6 points; median survival 8 years; HR 30.1, 95% CI 17.6-54), intermediate-2 (4 points; median 13.5 years; HR 12.7, 95% CI 7.1-23.0), intermediate-1 (2-3 points; median 20.7 years; HR 3.8, 95% CI 2.3-6.4) and low (0-1 points; median 47 years). The AAA model (Akaike Information Criterion [AIC] 621) performed better than IPSET (AIC 647) and was subsequently validated by an external University of Florence ET cohort (N = 485). None of the AAA variables predicted LFS while ALC <1.7 × 109 /L was associated with inferior MFFS (p = .01). Adverse mutations (p < .01) and karyotype (p < .01) displayed additional prognostic value without disqualifying the prognostic integrity of the AAA model. This study proposes a simple and globally applicable survival model for ET, which can be used as a platform for further molecular refinement. This study also suggests a potential role for immune-related biomarkers, as a prognostic tool in myeloproliferative neoplasms.

Anaplastic large cell lymphomas with equivocal DUSP22 FISH results: recommendations for clinical reporting and diagnostic evaluation

Anaplastic large cell lymphoma (ALCL), one of the most common T-cell lymphomas, shows unifying pathological features but is clinically and genetically heterogeneous. One genetic subgroup, characterized by recurrent DUSP22 rearrangements (R), has distinct morphologic, immunophenotypic, and molecular features and can be identified in routine pathology practice using a breakapart (BAP) fluorescence in situ hybridization (FISH) probe. However, some cases show equivocal BAP-FISH findings (BAP-FISHEQ) and the features of these cases are poorly understood. Here, we sought to characterize DUSP22 BAP-FISHEQ ALCLs further. First, we applied an immunohistochemistry (IHC) algorithm using TIA1, pSTAT3Y705, and LEF1, which can predict DUSP22-R with high accuracy. Among 37 BAP-FISHEQ ALCLs, 18 (49%) were IHC-algorithm positive (IHCPOS), 8 (21%) were IHC-algorithm negative (IHCNEG), and 11 (30%) were IHCEQ. In 32 BAP-FISHEQ cases, we also applied a dual-color, dual-fusion (D-FISH) probe for t(6;7)(p25.3;q32.3), which accounts for 45% of DUSP22-R ALCLs. Among BAP-FISHEQ cases, D-FISH was positive in 10/18 IHCPOS cases (56%), 0/9 IHCEQ cases (0%), and 0/5 IHCNEG cases (0%). Median survival in BAP-FISHEQ ALCLs was 105 months, intermediate between BAP-FISHPOS ALCLs (median survival not reached) and BAP-FISHNEG ALCLs (19 months). Thus, DUSP22 BAP-FISHEQ ALCLs are clinicopathologically heterogeneous, likely due to an admixture of cases with an unbalanced DUSP22-R and cases with focal deletions without rearrangement. For clinical reporting, we recommend that DUSP22 BAP-FISHEQ ALCLs be reported as equivocal, and not be grouped with BAP-FISHPOS ALCLs. Clinical adoption of an IHC algorithm, possibly supplemented by t(6; 7) D-FISH, could facilitate genetic subtyping in about two-thirds of BAP-FISHEQ ALCLs.

VITREORETINAL INVOLVEMENT BY INDOLENT T-CELL LYMPHOPROLIFERATIVE DISORDER OF THE GASTROINTESTINAL TRACT DIAGNOSED BY FLUORESCENCE IN SITU HYBRIDIZATION

PURPOSE

The purpose of this study was to describe an exceedingly rare presentation of secondary vitreoretinal involvement by the uncommon entity "indolent T-cell lymphoproliferative disorder of the gastrointestinal tract" and illustrate the utility of fluorescence in situ hybridization for diagnosis.

METHODS

This is a case report.

RESULTS

A 57-year-old woman with presumed iritis on chronic topical prednisolone acetate presented with increased vitreous opacities in the right eye. She had a history of biopsy-confirmed indolent T-cell lymphoproliferative disorder of the gastrointestinal tract involving the stomach and duodenum, JAK2 -rearrangement positive, controlled on maintenance oral methotrexate. Vitreous biopsy was unremarkable with small CD3-positive and CD4-positive and CD20-negative lymphocytes, along with histiocytes and fibroblasts. Immunostains showed CD4 positivity, and fluorescence in situ hybridization revealed a JAK2 gene rearrangement, consistent with the patient's previously diagnosed indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. Intravitreal methotrexate injections were started in the right eye. MRI of the brain and lumbar puncture with cytology, MYD88 , IL10, and flow cytometry performed at the time of right eye vitreoretinal lymphoma diagnosis revealed no evidence of central nervous system lymphoma, but subsequent bone marrow biopsy demonstrated 5% involvement by indolent T-cell lymphoproliferative disorder of the gastrointestinal tract, JAK2 -rearrangement positive, with a lung nodule on PET computed tomography. She returned 4 months later with fatigue, night sweats, and blurry vision in the left eye with vitreous and anterior chamber cellular infiltration and retinal vasculitis.

CONCLUSION

T-cell vitreoretinal lymphoma is rare, and diagnosis can be challenging. Despite inconclusive cytology in this case, interphase fluorescence in situ hybridization detected a JAK2 gene rearrangement, which confirmed the involvement by indolent T-cell lymphoproliferative disorder of the gastrointestinal tract and prompted appropriate treatment and workup for recurrent systemic or central nervous system lymphoma.

"Quadruple-hit" primary testicular diffuse large B-cell lymphoma with MYD88 L265P mutation, IGH::MYC, and IRF4- and BCL6-rearrangements

Classification of DLBCL relies on clinical, immunohistochemical, and genetic information. We report a case of primary testicular diffuse large B-cell lymphoma (PT-DLBCL) with a hitherto unreported constellation of pathologic findings to illustrate the challenges of DLBCL classification. A standard hematopathology workup was followed by gene expression profiling (GEP) to determine the DLBCL cell of origin (COO). A 75-year-old man presented with a unilateral testicular mass that had developed over the course of 1 month. Pathologic examination demonstrated involvement by DLBCL. Clinical staging revealed no systemic disease. Genetic testing showed an MYD88 mutation, as well as IGH::MYC and IRF4- and BCL6-rearrangements. Gene expression profiling demonstrated an activated B-cell expression profile. This case highlights the genetic complexity of DLBCL arising in the testis and questions the clinical significance of the identified genetic abnormalities.

Blast phase myeloproliferative neoplasm with prior exposure to ruxolitinib: comparative analysis of mutations and survival

Not available.

Obesity in adult acute myeloid leukemia is not associated with inferior response or survival even when dose capping anthracyclines: An ECOG-ACRIN analysis

BACKGROUND

Obesity (body mass index [BMI] ≥30 kg/m2 ) is an important epidemiological risk factor for developing acute myeloid leukemia (AML). Therefore, the authors studied the association of obesity with clinical and genetic phenotype and its impact on outcome in adults with AML.

METHODS

The authors analyzed BMI in 1088 adults who were receiving intensive remission induction and consolidation therapy in two prospective, randomized therapeutic clinical trials of the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network: E1900 (ClinicalTrials.gov identifier NCT00049517; patients younger than 60 years) and E3999 (ClinicalTrials.gov identifier NCT00046930; patients aged 60 years or older).

RESULTS

Obesity was prevalent at diagnosis (33%) and, compared with nonobesity, was associated with intermediate-risk cytogenetics group (p = .008), poorer performance status (p = .01), and a trend toward older age (p = .06). Obesity was not associated with somatic mutations among a selected 18-gene panel that was tested in a subset of younger patients. Obesity was not associated with clinical outcome (including complete remission, early death, or overall survival), and the authors did not identify any patient subgroup that had inferior outcomes based on BMI. Obese patients were significantly more likely to receive <90% of the intended daunorubicin dose despite protocol specification, particularly in the E1900 high-dose (90 mg/m2 ) daunorubicin arm (p = .002); however, this did not correlate with inferior overall survival on multivariate analysis (hazard ratio, 1.39; 95% confidence interval, 0.90-2.13; p = .14).

CONCLUSIONS

Obesity is associated with unique clinical and disease-related phenotypic features in AML and may influence physician treatment decisions regarding daunorubicin dosing. However, the current study demonstrates that obesity is not a factor in survival, and strict adherence to body surface area-based dosing is not necessary because dose adjustments do not affect outcomes.

A TRIP11:: FLT3 gene fusion in a patient with myeloid/lymphoid neoplasm with eosinophilia and tyrosine kinase gene fusions: a case report and review of the literature

Myeloid/lymphoid neoplasms with FLT3 gene fusions have recently been included among myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK) in the World Health Organization classification and International Consensus Classification. As this entity remains remarkably rare, its scope and phenotypic features are evolving. In this report, we describe a 33-yr-old male with MLN-TK. Conventional chromosome analysis revealed a t(13;14)(q12;q32). Further analysis with mate-pair sequencing (MPseq) confirmed a TRIP11::FLT3 gene fusion. A diagnosis of MLN-TK was rendered. To the best of our knowledge, we report the third case of MLN-TK with a TRIP11::FLT3 gene fusion. In contrast to previously described cases, our case exhibited distinctly mild clinical features and disease behavior, emphasizing the diverse spectrum of MLN-TK at primary presentation and variability in disease course. MLN-TK with FLT3 gene fusions are a genetically defined entity which may be targetable with tyrosine kinase inhibitors with anti-FLT3 activity. Accordingly, from diagnostic and therapeutic viewpoints, genetic testing for FLT3 rearrangements using fluorescence in situ hybridization (FISH) or sequencing-based assays should be pursued for patients with chronic eosinophilia.

Characterization of unusual iAMP21 B-lymphoblastic leukemia (iAMP21-ALL) from the Mayo Clinic and Children's Oncology Group

Acute lymphoblastic leukemia (B-ALL) with intrachromosomal amplification of chromosome 21 (iAMP21-ALL) represents a recurrent high-risk cytogenetic abnormality and accurate identification is critical for appropriate clinical management. Identification of iAMP21-ALL has historically relied on fluorescence in situ hybridization (FISH) using a RUNX1 probe. Current classification requires ≥ five copies of RUNX1 per cell and ≥ three additional copies of RUNX1 on a single abnormal iAMP21-chromosome. We sought to evaluate the performance of the RUNX1 probe in the identification of iAMP21-ALL. This study was a retrospective evaluation of iAMP21-ALL in the Mayo Clinic and Children's Oncology Group cohorts. Of 207 cases of iAMP21-ALL, 188 (91%) were classified as "typical" iAMP21-ALL, while 19 (9%) cases were classified as "unusual" iAMP21-ALL. The "unusual" iAMP21 cases did not meet the current definition of iAMP21 by FISH but were confirmed to have iAMP21 by chromosomal microarray. Half of the "unusual" iAMP21-ALL cases had less than five RUNX1 signals, while the remainder had ≥ five RUNX1 signals with some located apart from the abnormal iAMP21-chromosome. Nine percent of iAMP21-ALL cases fail to meet the FISH definition of iAMP21-ALL demonstrating that laboratories are at risk of misidentification of iAMP21-ALL when relying only on the RUNX1 FISH probe. Incorporation of chromosomal microarray testing circumvents these risks.

Immunohistochemical Approach to Genetic Subtyping of Anaplastic Large Cell Lymphoma

Anaplastic large cell lymphoma (ALCL) can be classified genetically based on rearrangements (R) of the ALK , TP63 , and/or DUSP22 genes. ALK- R defines a specific entity, ALK-positive ALCL, while DUSP22- R and TP63- R define subgroups of ALK-negative ALCLs with distinct clinicopathologic features. ALK -R and TP63 -R produce oncogenic fusion proteins that can be detected by immunohistochemistry. ALK immunohistochemistry is an excellent surrogate for ALK- R and screening with p63 immunohistochemistry excludes TP63- R in two third of ALCLs. In contrast, DUSP22 -R does not produce a fusion protein and its identification requires fluorescence in situ hybridization. However, DUSP22- R ALCL has a characteristic phenotype including negativity for cytotoxic markers and phospho-STAT3 Y705 . Recently, we also identified overexpression of the LEF1 transcription factor in DUSP22- R ALCL. Here, we sought to validate this finding and examine models for predicting DUSP22- R using immunohistochemistry for LEF1 and TIA1 or phospho-STAT3 Y705 . We evaluated these 3 markers in our original discovery cohort (n=45) and in an independent validation cohort (n=46) of ALCLs. The correlation between DUSP22- R and LEF1 expression replicated strongly in the validation cohort ( P <0.0001). In addition, we identified and validated a strategy using LEF1 and TIA1 immunohistochemistry that predicted DUSP22- R with positive and negative predictive values of 100% after exclusion of indeterminate cases and would eliminate the need for fluorescence in situ hybridization in 65% of ALK-negative ALCLs. This approach had similar results in identifying DUSP22- R in the related condition, lymphomatoid papulosis. Together with previous data, these findings support a 4-marker immunohistochemistry algorithm using ALK, LEF1, TIA1, and p63 for genetic subtyping of ALCL.

A dynamic 3-factor survival model for acute myeloid leukemia that accounts for response to induction chemotherapy

The current study was approached with the assumption that response to induction chemotherapy, in acute myeloid leukemia (AML), overshadows pre-treatment risk variables in predicting survival and therefore be used as an anchor for a simplified risk model. We considered 759 intensively-treated patients with AML, not promyelocytic: median age 60 years; primary 66%, secondary 25%, and therapy-related 9%; European LeukemiaNet cytogenetic risk category favorable 8%, intermediate 61%, and adverse 31%. Complete remission with (CR) or without (CRi) count recovery was achieved in 608 (80%) patients. After a median follow-up of 22 months, 503 deaths, 272 relapses, and 257 allogeneic hematopoietic stem cell transplants (AHSCTs) were recorded. Multivariable analysis identified failure to achieve CR/CRi (HR 3.8, 95% CI 3.1-4.8), adverse karyotype (2.2, 1.8-2.8), and age >55 years (2.1, 1.6-2.7) as main risk factors for survival. HR-weighted scoring resulted in four-tiered risk stratification: low (0 points; N=183), intermediate-1 (1 point; N=331), intermediate-2 (2 points; N=117), and high (≥3 points; N=128), with respective median survival (5-year rate) not reached (68%), 34 (37%), 13 (20%), and 5 (5%) months (p <0.001). FLT3-ITD mutation was associated with inferior survival in intermediate-1 (p=0.004) and TP53 in intermediate-2 (p=0.06) and high (p=0.02) risk disease; the latter was fully accounted for by the close association between TP53 mutation and complex/monosomal karyotype while the observations regarding FLT3-ITD were not affected by treatment with midostaurin. AHSCT had a favorable impact on survival, most apparent in intermediate-1 (p<0.001), intermediate-2 (p=0.03), and high (p=0.01) risk disease. The proposed 3-factor survival model offers a novel prototype that is amenable to further enhancement by molecular information and was validated in an external cohort of 1,032 intensively-treated AML patients. This article is protected by copyright. All rights reserved.

Typical, atypical and cryptic t(15;17)(q24;q21) (PML::RARA) observed in acute promyelocytic leukemia: a retrospective review of 831 patients with concurrent chromosome and PML::RARA dual-color dual-fusion FISH studies

The diagnosis of acute promyelocytic leukemia (APL) relies on the identification of PML::RARA fusion. While the majority of APL cases harbor a typical t(15;17)(q24;q21), atypical genetic mechanisms leading to the oncogenic PML::RARA fusion have been reported yet their frequency and scope remain poorly characterized. We assessed the genetic findings of 831 cases with APL investigated with concurrent chromosome banding analysis and dual-color dual-fusion fluorescence in situ hybridization (D-FISH) analysis at our institution over an 18.5-year timeframe. Seven-hundred twenty-three (87%) cases had a typical balanced t(15;17) with both testing modalities. Atypical karyotypic results including complex translocations, unbalanced rearrangements and insertional events occurred in 50 (6%) cases, while 6 (0.7%) cases were cryptic by conventional chromosome studies despite PML::RARA fusion by D-FISH evaluation. Atypical FISH patterns were observed in 48 (6%) cases despite apparently balanced t(15;17) on chromosome banding analysis. Two-hundred fifty (30%) cases displayed additional chromosome abnormalities of which trisomy/tetrasomy 8 (37%), del(7q)/add(7q) (12%) and del(9q) (7%) were most frequent. Complex and very complex karyotypes were observed in 81 (10%) and 34 (4%) cases, respectively. In addition, 4 (0.5%) cases presented as an apparently doubled, near-tetraploid stemline clone. This report provides the largest appraisal of cytogenetic findings in APL with conventional chromosome and PML::RARA D-FISH analysis. By characterizing the frequency and breadth of typical and atypical results through the lens of these cytogenetic testing modalities, this study serves as a pragmatic source of information for those involved in the investigation of APL in both the clinical and research laboratory settings.

Cytogenetic abnormalities in essential thrombocythemia: Clinical and molecular correlates and prognostic relevance in 809 informative cases

Cytogenetic studies among 809 consecutive patients with essential thrombocythemia (ET; median age 59 years; 65% females) revealed normal karyotype in 754 (93%), loss of chromosome Y only (-Y) in 16 (2%), and abnormalities other than -Y in 39 (4.8%), the most frequent being sole 20q- (n = 8). At presentation, abnormal karyotype, excluding -Y, was associated with older age (p = 0.04), higher leukocyte count (p = 0.03) and arterial thrombosis history (p = 0.02); no associations were apparent for JAK2/CALR/MPL mutations whereas ASXL1 mutations clustered with normal karyotype/-Y and TP53 with abnormal karyotype. Survival was significantly shorter in patients with abnormal karyotype or -Y, compared to those with normal karyotype (median 12, 10, and 21 years, respectively; p < 0.0001). During multivariable analysis that included IPSET (international prognostic score for ET) variables, abnormal karyotype (p < 0.01, HR 2.0), age >60 years (p < 0.01, HR 4.5), leukocytosis >11 × 10⁹/L (p < 0.01, HR 1.5), and male gender (p < 0.01, HR 1.4) were independently associated with inferior survival; abnormal karyotype and age >60 years remained significant, along with SF3B1/SRSF2/U2AF1/TP53 mutations (p = 0.04; HR 2.9), when the latter was included in the multivariable model. The current study suggests prognostic relevance for karyotype in ET.

Recurrent Chromosomal Abnormalities in Tissues Involved by Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

OBJECTIVES

Prognostically relevant chromosomal abnormalities in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) are routinely identified by fluorescence in situ hybridization (FISH) on peripheral blood or bone marrow specimens. We studied the prevalence of chromosomal abnormalities on extramedullary tissues involved by CLL/SLL and evaluated their association with prominent proliferation centers (PPCs).

METHODS

FISH for recurrent abnormalities in CLL/SLL was performed on formalin-fixed, paraffin-embedded biopsy sections. PPCs were identified on H&E-stained sections. Available FISH results on peripheral blood or bone marrow specimens were also reviewed.

RESULTS

Recurrent FISH abnormalities were detected in 69% of 320 CLL/SLL biopsy specimens studied, including +12 (35%), 13q- (24%), 11q- (15%), 17p- (6%), 6q- (2%), and IGH/BCL2 (0.9%). Forty-three patients had abnormal blood or bone marrow FISH analyses, of whom 7 (16%) had discordant +12 and/or 13q-, and 3 (7%) had discordant 17p- or 11q-. Morphology was positive (17%), negative (78%), or equivocal (6%) for PPCs on 247 evaluable biopsy specimens, a finding not significantly associated with FISH results (P = .7).

CONCLUSIONS

Trisomy 12 is overrepresented in tumoral CLL/SLL involvement, compared with the known predominance of 13q- in blood. Discrepancies between leukemic and tissue FISH findings are occasionally encountered. FISH results do not correlate with the presence of PPCs.

A simple additive staging system for newly diagnosed multiple myeloma

Risk stratification in multiple myeloma is important for prognostication, patient selection for clinical trials, and comparison of treatment approaches. We developed and validated a staging system that incorporates additional FISH abnormalities not included in the R-ISS and reflects the additive effects of co-occurring high-risk disease features. We first evaluated the prognostic value of predefined cytogenetic and laboratory abnormalities in 2556 Mayo Clinic patients diagnosed between February 2004 and June 2019. We then used data from 1327 patients to develop a risk stratification model and validated this in 502 patients enrolled in the MMRF CoMMpass study. On multivariate analysis, high-risk IgH translocations [risk ratio (RR): 1.7], 1q gain/amplification (RR: 1.4), chromosome17 abnormalities (RR: 1.6), ISS III (RR: 1.7), and elevated LDH (RR: 1.3) were independently associated with decreased overall survival (OS). Among 1327 evaluable patients, OS was 11.0 (95% CI: 9.2–12.6), 7.0 (95% CI: 6.3–9.2), and 4.5 (95% CI: 3.7–5.2) years in patients with 0 (stage I), 1 (stage II), and ≥2 (stage III) high-risk factors, respectively. In the MMRF cohort, median OS was 7.8 (95% CI: NR-NR), 6.0 (95% CI: 5.7-NR), and 4.3 (95% CI: 2.7-NR) years in the 3 groups, respectively (P < 0.001). This 5-factor, 3-tier system is easy to implement in practice and improves upon the current R-ISS.

European LeukemiaNet-defined primary refractory acute myeloid leukemia: the value of allogeneic hematopoietic stem cell transplant and overall response

We sought to appraise the value of overall response and salvage chemotherapy, inclusive of allogeneic hematopoietic stem cell transplant (AHSCT), in primary refractory acute myeloid leukemia (prAML). For establishing consistency in clinical practice, the 2017 European LeukemiaNet (ELN) defines prAML as failure to attain CR after at least 2 courses of intensive induction chemotherapy. Among 60 consecutive patients (median age 63 years) correspondent with ELN-criteria for prAML, salvage was documented in 48 cases, 30/48 (63%) being administered intensive chemotherapy regimens and 2/48 consolidated with AHSCT as first line salvage. 13/48 (27%) attained response: CR, 7/13 (54%), CRi, 2/13 (15%), MLFS, 4/13 (31%). The CR/CRi rate was 9/48 (19%), with CR rate of 7/48 (15%). On univariate analysis, intermediate-risk karyotype was the only predictor of response (44% vs 17% in unfavorable karyotype; P = 0.04). Administration of any higher-dose (>1 g/m²) cytarabine intensive induction (P = 0.50), intensive salvage chemotherapy (P = 0.72), targeted salvage (FLT3 or IDH inhibitors) (P = 0.42), greater than 1 salvage regimen (P = 0.89), age < 60 years (P = 0.30), and de novo AML (P = 0.10) did not enhance response achievement, nor a survival advantage. AHSCT was performed in 12 patients with (n = 8) or without (n = 4) CR/CRi/MLFS. 1/2/5-year overall survival (OS) rates were 63%/38%/33% in patients who received AHSCT (n = 12) vs 27%/0%/0% in those who achieved CR/CRi/MLFS but were not transplanted (n = 5), vs 14%/0%/0% who were neither transplanted nor achieved CR/CRi/MLFS (n = 43; P < 0.001); the median OS was 18.6, 12.6 and 5.6 months, respectively. Although CR/CRi/MLFS bridged to AHSCT (n = 8), appeared to manifest a longer median OS (20 months), vs (13.4 months) for those with no response consolidated with AHSCT (n = 4), the difference was not significant P = 0.47. We conclude AHSCT as indispensable for securing long-term survival in prAML (p = 0.03 on multivariate analysis), irrespective of response achievement.

Utilizing next-generation sequencing to characterize a case of acute myeloid leukemia with t(4;12)(q12;p13) in the absence of ETV6/CHIC2 and ETV6/PDGFRA gene fusions

The t(4;12)(q12;p13) has been rarely reported in both myeloid/lymphoid neoplasms with eosinophilia (ETV6/PDGFRA gene fusion) and acute myeloid leukemia (AML) (ETV6/CHIC2 gene fusion). The ability to accurately characterize t(4;12) is critical as myeloid neoplasms with PDGFRA rearrangements may be amenable to tyrosine kinase inhibitor (TKI) therapy. Herein, we describe a 60-year-old male with newly diagnosed AML and t(4;12)(q12;p13) by conventional chromosome studies. While the ETV6 break-apart fluorescence in situ hybridization (FISH) probe set demonstrated a balanced ETV6 gene rearrangement, the FIP1L1/CHIC2/PDGFRA tri-color and PDGFRA break-apart FISH probe sets could not resolve the ETV6 gene fusion partner. Mate-pair sequencing (MPseq), a next-generation sequencing assay, was subsequently performed and identified an ETV6 gene rearrangement (at 12p13) that involved an intergenic chromosomal region at 4q12, located between the CHIC2 and PDGFRA gene regions. Having excluded involvement by the PDGFRA gene region, the patient will not be considered for TKI therapy at any point during his medical management. The accurate characterization of structural rearrangements by NGS-based technologies, as demonstrated in this case, highlights the clinical relevance and potential impact on patient medical management of modern cytogenetic techniques.

Prognostic significance of acquired 1q22 gain in multiple myeloma

Gain of 1q22 at diagnosis portends poorer outcomes in multiple myeloma (MM), but the prognostic significance of acquired 1q22 gain is unknown. We identified 63 MM patients seen at Mayo Clinic from 1/2004 to 12/2019 without 1q22 gain at diagnosis who acquired it during follow up and compared them to 63 control patients who did not acquire 1q22 gain with similar follow up. We also compared outcomes in the acquired 1q22 gain group with outcomes in 126 patients with 1q22 gain present at diagnosis. The incidence of acquired 1q22 gain was 6.1% (median follow-up 6.8 years); median time to acquisition was 5.0 years (range: 0.7-11.5 years). Abnormalities on baseline fluorescence in situ hybridization (FISH) included trisomies (54%) and monosomy 13 (39%); 16 (25%) had high-risk (HR) translocations or del(17p). Median progression-free survival with front line therapy was 29.5 months in patients with acquired 1q22 gain, versus 31.4 months in control patients (p = .34) and 31.2 months in patients with de novo 1q22 gain (p = .04). Median overall survival (OS) from diagnosis was 10.9 years in patients with acquired 1q22 gain, versus 13.0 years in control patients (p = .03) and 6.3 years in patients with de novo 1q22 gain (p = .01). Presence of HR FISH at baseline increased risk of 1q22 gain acquisition. We demonstrate that acquisition of 1q22 gain is a significant molecular event in MM, associated with reduced OS. Among HR patients for whom this clonal evolution is determined, a risk-adapted approach and/or clinical trial should be considered.

Identification of a Cryptic t(8;20;21)(q22;p13;q22) Resulting in RUNX1T1/RUNX1 Fusion in a Patient with Newly Diagnosed Acute Myeloid Leukemia

The detection of recurrent genetic abnormalities in acute myeloid leukemia (AML), including RUNX1T1/RUNX1 gene fusion, is critical for optimal medical management. Herein, we report a 45 year old woman with newly diagnosed AML and conventional chromosome studies that revealed an apparently balanced t(8;20)(q22;p13) in all 20 metaphases analyzed. A RUNX1T1/RUNX1 dual-color dual-fusion fluorescence in situ hybridization (FISH) probe set was subsequently performed and revealed a RUNX1T1/RUNX1 gene fusion. Metaphase FISH studies performed on abnormal metaphases revealed a cryptic, complex translocation resulting in RUNX1T1/RUNX1 fusion, t(8;20;21)(q22;p13;q22). This case study shows the importance of performing FISH studies or other high-resolution genetic testing concurrently with conventional chromosome studies for the detection of cryptic recurrent gene fusions in AML, particularly a focused genetic evaluation such as RUNX1T1/RUNX1 gene fusion, when specific abnormalities involving 8q22 are identified.

Tipifarnib as maintenance therapy did not improve disease-free survival in patients with acute myelogenous leukemia at high risk of relapse: Results of the phase III randomized E2902 trial

PURPOSE

Despite the achievement of complete remission with chemotherapy in patients with acute myeloid leukemia (AML), relapse is common and the majority of patients will die of their disease. Patients who achieve a remission after refractory or relapsed disease as well as elderly patients have a very high rate of relapse even if they achieve a complete remission. A phase 3 randomized ECOG-ACRIN-led intergroup study was conducted to determine whether post-remission therapy with the farnesyl transferase inhibitor, tipifarnib (R115777), improved the disease-free survival (DFS) of adult patients with AML in complete remission (CR), at high risk for relapse.

PATIENTS AND METHODS

Adult patients with AML in remission after salvage therapy and/or over age 60 in first remission were enrolled in this study. They were randomly assigned to treatment with tipifarnib or observation (control). The primary objective was to compare the disease-free survival (DFS) between the two arms based on intention to treat, which includes all randomized patients.

RESULTS

One hundred and forty-four patients were enrolled on the study. Median DFS was 8.9 vs 5.3 months, for tipifarnib vs observation (one-sided p = 0.026) and did not cross the pre-specified boundary to call the study positive. For the 134 eligible patients, median DFS was 10.8 vs 5.3 months for those randomized to tipifarnib vs observation (one-sided p = 0.008). Moreover in an ad hoc evaluation of all women (n = 71) median DFS was 12.1 vs 3.9 months for tipifarnib vs observation (one-sided p = 0.0004) while median OS was 26.5 vs 8.4 months respectively (one-sided p = 0.001).

CONCLUSION

This study was not able to demonstrate a benefit to tipifarnib as maintenance therapy in patients with AML in remission. While subsets of patients may indeed benefit, additional studies would be needed to elucidate that benefit which is unlikely given that other seemingly better options have since become available.

Clonally-Related Composite Classic Hodgkin Lymphoma and Follicular Lymphoma

Introduction/Objective

Composite classic Hodgkin lymphoma and follicular lymphoma (CHLFL), defined as CHL and FL occurring simultaneously at the same site, is rare and poorly understood. While both Hodgkin/Reed-Sternberg (HRS) cells and FL are thought to be derived from germinal center B-cells, the relationship between CHL and FL when coexistent is unclear. Here, we present two cases of CHLFL and show that the CHL and FL components have a clonal relationship by FISH.

Methods/Case Report

Case #1 is a 50-year-old man with abdominal and mediastinal lymphadenopathy. An excised mesenteric lymph node showed two distinct components diagnostic for FL, grade 1-2 and CHL. Case #2 is a 63-year- old woman with a history of FL with transformation to diffuse large B-cell lymphoma. Cytogenetic studies showed a complex karyotype with an add(9p), del(10q), and trisomy 16. Post-treatment imaging revealed left axillary adenopathy. An excised axillary lymph node showed CHL with peripheral areas of FL, grade 3A.

Both cases had areas of typical FL with BCL2-positive phenotype and no significant CD30/CD15 expression. HRS cells were CD45/CD20-negative, expressed CD30 (strong), CD15, and PAX5, and were present in a mixed inflammatory background. No EBV RNA was present by in situ hybridization. Interestingly, HRS cells in case #1 expressed both BCL6 and BCL2.

FISH was performed in both cases. Case #1 had a BCL2 rearrangement in 48% of FL nuclei and in 100% of HRS cells. In case #2, targeted probes were used based on prior cytogenetic results. Here, 47% of FL nuclei and 44% of HRS cells had a 16p duplication; additionally, 32% of HRS cells had an unbalanced IGH rearrangement with loss of the IGH variable region, suggesting possible clonal evolution. No rearrangement of BCL2 or BCL6 was present.

An additional 27 CHLFL cases from the literature were reviewed. CHLFL was mostly nodal and occurred in late adulthood in patients with or without a history of FL. It presented at advanced clinical stage, with a 5-year overall survival of 22%. BCL2 expression in HRS cells was common. Bone marrow involvement was 45% (5/11) and consisted of FL exclusively. Five of six tested cases demonstrated BCL2/IGH rearrangement in both FL and HRS cells.

Results (if a Case Study enter NA)

NA

Conclusion

Composite CHL and FL are often clonally related and may share a common progenitor B-cell origin – likely a germinal center B-cell – from which additional genetic abnormalities are acquired to develop two distinct lymphomas.

Comparative study of therapy-related and de novo adult b-cell acute lymphoblastic leukaemia

We report a comparative analysis of patients with therapy‐related acute lymphoblastic leukaemia (tr‐ALL) vs de novo ALL. We identified 331 patients with B‐ALL; 69 (21%) were classified as tr‐ALL. The most common prior malignancies were breast (23·2%) and plasma cell disorders (20·3%). Patients with tr‐ALL were older (median 63·2 vs. 46·2 years, P < 0.001), more often female (66·7% vs. 43·5%, P < 0·001), and more likely to have hypodiploid cytogenetics (18·8% vs. 5·0%, P < 0·001). In multivariable analysis, patients with tr‐ALL were less likely to achieve complete remission [odds ratio (OR) = 0·16, P < 0·001] and more likely to be minimal residual disease‐positive (OR = 4·86, P = 0·01) but had similar OS after diagnosis and allo‐haematopoietic cell transplantation.

The Prognostic Role of MYC Structural Variants Identified by NGS and FISH in Multiple Myeloma

PURPOSE

Structural variants (SV) of the MYC gene region are common in multiple myeloma and influence disease progression. However, the prognostic significance of different MYC SVs in multiple myeloma has not been clearly established.

EXPERIMENTAL DESIGN

We conducted a retrospective study of multiple myeloma comparing MYC SV subtypes identified by next-generation sequencing (NGS) and FISH to MYC expression and disease survival using 140 cases from Mayo Clinic and 658 cases from the MMRF CoMMpass study.

RESULTS

MYC SVs were found in 41% of cases and were classified into nine subtypes. A correlation between the presence of a MYC SV and increased MYC expression was identified. Among the nine MYC subtypes, the non-immunoglobulin (non-Ig) insertion subtype was independently associated with improved outcomes, while the Ig insertion subtype, specifically involving the IgL gene partner, was independently associated with poorer outcomes compared with other MYC SV subtypes. Although the FISH methodology failed to detect approximately 70% of all MYC SVs, those detected by FISH were associated with elevated MYC gene expression and poor outcomes suggesting a different pathogenic role for FISH-detected MYC subtypes compared with other MYC subtypes.

CONCLUSIONS

Understanding the impact of different MYC SVs on disease outcome is necessary for the reliable interpretation of MYC SVs in multiple myeloma. NGS approaches should be considered as a replacement technique for a more comprehensive evaluation of the multiple myeloma clone.

Increased complexity of t(11;14) rearrangements in plasma cell neoplasms compared with mantle cell lymphoma

Plasma cell neoplasms (PCN) and mantle cell lymphoma (MCL) can both harbor t(11;14)(q13;q32) (CCND1/IGH), usually resulting in cyclin D1 overexpression. In some cases, particularly at low levels of disease, it can be morphologically challenging to distinguish between these entities in the bone marrow (BM) since PCN with t(11;14) are often CD20-positive with lymphoplasmacytic cytology, while MCL can rarely have plasmacytic differentiation. We compared the difference in CCND1/IGH by fluorescence in situ hybridization (FISH) in PCN and MCL to evaluate for possible differentiating characteristics. We identified 326 cases of MCL with t(11;14) and 279 cases of PCN with t(11;14) from either formalin-fixed, paraffin-embedded tissue or fresh BM specimens. The "typical," balanced CCND1/IGH FISH signal pattern was defined as three total CCND1 signals, three total IGH signals, and two total fusion signals. Any deviation from the "typical" pattern was defined as an "atypical" pattern, which was further stratified into "gain of fusion" vs "complex" patterns. There was a significantly higher proportion of cases that showed an atypical FISH pattern in PCN compared with MCL (53% vs 27%, P < .0001). There was also a significantly higher proportion of cases that showed a complex FISH pattern in PCN compared with MCL (47% vs 17%, P < .0001). We confirmed these findings using mate-pair sequencing of 25 PCN and MCL samples. PCN more often have a complex CCND1/IGH FISH pattern compared with MCL, suggesting possible differences in the genomic mechanisms underlying these rearrangements in plasma cells compared with B cells.

Molecular classification improves risk assessment in adult BCR-ABL1-negative B-ALL

Genomic classification has improved risk assignment of pediatric, but not adult B-lineage acute lymphoblastic leukemia (B-ALL). The international UKALLXII/ECOG-ACRIN E2993 (#NCT00002514) trial accrued 1229 adolescent/adult patients with BCR-ABL1- B-ALL (aged 14 to 65 years). Although 93% of patients achieved remission, 41% relapsed at a median of 13 months (range, 28 days to 12 years). Five-year overall survival (OS) was 42% (95% confidence interval, 39, 44). Transcriptome sequencing, gene expression profiling, cytogenetics, and fusion polymerase chain reaction enabled genomic subtyping of 282 patient samples, of which 264 were eligible for trial, accounting for 64.5% of E2993 patients. Among patients with outcome data, 29.5% with favorable outcomes (5-year OS 65% to 80%) were deemed standard risk (DUX4-rearranged [9.2%], ETV6-RUNX1/-like [2.3%], TCF3-PBX1 [6.9%], PAX5 P80R [4.1%], high-hyperdiploid [6.9%]); 50.2% had high-risk genotypes with 5-year OS of 0% to 27% (Ph-like [21.2%], KMT2A-AFF1 [12%], low-hypodiploid/near-haploid [14.3%], BCL2/MYC-rearranged [2.8%]); 20.3% had intermediate-risk genotypes with 5-year OS of 33% to 45% (PAX5alt [12.4%], ZNF384/-like [5.1%], MEF2D-rearranged [2.8%]). IKZF1 alterations occurred in 86% of Ph-like, and TP53 mutations in patients who were low-hypodiploid (54%) and BCL2/MYC-rearranged (33%) but were not independently associated with outcome. Of patients considered high risk based on presenting age and white blood cell count, 40% harbored subtype-defining genetic alterations associated with standard- or intermediate-risk outcomes. We identified distinct immunophenotypic features for DUX4-rearranged, PAX5 P80R, ZNF384-R/-like, and Ph-like genotypes. These data in a large adult B-ALL cohort treated with a non-risk-adapted approach on a single trial show the prognostic importance of genomic analyses, which may translate into future therapeutic benefits.

De novo isolated myeloid sarcoma: comparative analysis of survival in 19 consecutive cases

Institutional database search (1999-2020) for acute myeloid leukaemia (AML) identified 109 cases of myeloid sarcoma (MS), of which 19 were isolated and presented de novo. The latter displayed longer survival (median 78 months), compared to MS with synchronous intramedullary AML (n = 32; median 16 months) and de novo AML without MS (n = 729; median 22 months; P = 0·13). However, the difference in survival was no longer apparent after accounting for bone marrow cytogenetic risk status (P = 0·67). Treatment-induced MS tumour resolution was not affected by the presence of intramedullary disease (P = 0·61). The current study clarifies the prognosis of de novo isolated MS, in the context of AML.