Childhood and Adolescent Relapsed/Refractory Aggressive B-Cell Lymphomas With t(8;14) and BCL2 Expression, Burkitt Lymphoma Versus Diffuse Large B-Cell Lymphoma: A Diagnostic Challenge.

We present 2 diagnostically challenging cases of pediatric/adolescent relapsed/refractory aggressive mature B-cell non-Hodgkin lymphoma (B-NHL) within the spectrum of Burkitt lymphoma and diffuse large B-cell lymphoma and illustrate the different therapeutic regimens that are employed for pediatric and adult cancer centers. Both cases displayed varying-sized lymphoma cells with occasional single prominent nucleoli and heterogeneous BCL2 expression. Cytogenetics revealed complex karyotypes with t(8:14)(q24.2;q32) and IGH::MYC rearrangement by FISH. Next generation sequencing revealed deleterious TP53 and MYC mutations. We concluded that both could be diagnosed as "DLBCL-NOS with MYC rearrangement" using the current pathologic classifications, 2022 International Consensus Classification (ICC) and World Health Organization Classifications of Haematolymphoid Tumors (WHO-HAEM5). This report illustrates diagnostic challenges and treatment dilemmas that may be encountered, particularly for adolescent and young adults (AYA).

ETNK1 mutation occurs in a wide spectrum of myeloid neoplasms and is not specific for atypical chronic myeloid leukemia.

BACKGROUND: ETNK1 mutation has been suggested as a useful tool to support the diagnosis of atypical chronic myeloid leukemia. ETNK1 mutations, however, occur in other myeloid neoplasms. METHODS: The authors assessed the clinicopathologic and molecular genetic features of 80 ETNK1-mutated myeloid neoplasms. RESULTS: Thirty-seven neoplasms (46%) were classified as myelodysplastic syndrome, 17 (21%) were classified as myelodysplastic/myeloproliferative neoplasm, 14 (18%) were classified as acute myeloid leukemia, and 12 (15%) were classified as myeloproliferative neoplasm. ETNK1 mutations were detected at the first test in 96% of patients, suggesting that ETNK1 mutation is an early event in pathogenesis. ETNK1 mutations represented the dominant clone in 63% of patients and was persistently dominant in 93%. The variant allele frequencies were usually higher in acute myeloid leukemia and increased upon leukemic transformation. ETNK1 mutation was accompanied by coexisting mutations in all patients, with ASXL1 (50%), TET2 (25%), EZH2 (24%), RUNX1 (24%), and SRSF2 (24%) mutations being the most common. Neoplasms with ETNK1 mutations were associated with morphologic dysplasia, increased blasts, myelofibrosis, and noncomplex karyotypes. With a median follow-up of 16.5 months, 30 patients died, 44 had persistent disease, and four achieved complete remission after stem cell transplantation. CONCLUSIONS: ETNK1 mutation is present in various myeloid neoplasms, often as an early event and a dominant clone and always with concurrent mutations. It may play an important role in the pathogenesis and progression of myeloid neoplasms by causing DNA damage and inducing other mutations and genomic instability, and it may serve as a potential therapeutic target. ETNK1 mutation is not disease-specific and should be interpreted with caution to classify myeloid neoplasms.

CD30 expression is frequently decreased in relapsed classic Hodgkin lymphoma after anti-CD30 CAR T-cell therapy.

Chimeric antigen receptor (CAR) T-cells anti-CD30 is an innovative therapeutic option that has been used to treat cases of refractory/relapsed (R/R) classic Hodgkin lymphoma (CHL). Limited data are available regarding the CD30 expression status of patients who relapsed after this therapy. This is the first study to show decreased CD30 expression in R/R CHL in patients (n = 5) who underwent CAR T-cell therapy in our institution between 2018 and 2022. Although conventional immunohistochemical assays showed decreased CD30 expression in neoplastic cells in all cases (8/8) the tyramide amplification assay and RNAScope in situ hybridisation detected CD30 expression at different levels in 100% (n = 8/8) and 75% (n = 3/4), respectively. Hence, our findings document that certain levels of CD30 expression are retained by the neoplastic cells. This is not only of biological interest but also diagnostically important, as detection of CD30 is an essential factor in establishing a diagnosis of CHL.

From the archives of MD Anderson Cancer Center: Sporadic Burkitt lymphoma with a complex karyotype and SOX11 expression.

Burkitt lymphoma (BL) is a mature B-cell neoplasm arising from germinal center B-cells. There are three epidemiological variants of which the sporadic variant is most prevalent in developed countries representing 1-2 % of all lymphomas in adults. Patients usually present with bulky abdominal masses and ~ 30 % have bone marrow involvement. BL is characterized by a germinal center B-cell immunophenotype and usually has a simple karyotype. Here we report an unusual case of sporadic BL in a 44-year-old man and we use this case to review sporadic BL in adults. The patient presented with a cecal mass and bone marrow involvement. Biopsy of the cecal mass and bone marrow evaluation showed infiltration by intermediate-size lymphoma cells positive for monotypic kappa, CD10, CD19, CD20, CD22, CD38 bright, CD43, CD45, Bcl6 and ROR1, and negative for CD11c, CD23, CD30, CD44, CD200 and Bcl2. As expected, the lymphoma cells were strongly positive for MYC and Ki-67 showed a proliferation rate of nearly 100 %, but the cells were also positive for SOX11 and cytoplasmic LEF1. Conventional chromosomal analysis revealed t(8;14) as part of a complex karyotype. Based on our literature review, and is shown in this case, sporadic BL in adults shows some differences with the classic description of BL in children. We also discuss the differential diagnosis of BL.

Ibrutinib-rituximab followed by R-HCVAD as frontline treatment for young patients (≤65 years) with mantle cell lymphoma (WINDOW-1): a single-arm, phase 2 trial.

BACKGROUND: Induction with ibrutinib and rituximab provides an opportunity to minimise chemotherapy exposure, because upfront use of these targeted therapies could result in remission without chemotherapy and allow for consolidation with only four cycles of chemotherapy instead of the conventional eight. We aimed to determine the activity and safety of ibrutinib-rituximab induction followed by shortened chemoimmunotherapy (four cycles) with rituximab plus hyper-fractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (R-HCVAD) alternating with methotrexate-cytarabine in previously untreated patients with mantle cell lymphoma. METHODS: We did a single-centre, single-arm, phase 2 trial in previously untreated patients with mantle cell lymphoma. Eligible patients were aged 65 years or younger and had serum bilirubin of less than 1·5 mg/dL, creatinine clearance of 30 mL/min or more, Eastern Cooperative Oncology Group performance status of 2 or less, and cardiac ejection fraction 50% or more by echocardiogram. Patients received 12 cycles of ibrutinib-rituximab induction (part A; oral ibrutinib 560 mg daily and intravenous rituximab 375 mg/m2 weekly for the first 4 weeks and then on day 1 of cycles 3-12). As soon as patients had a complete response, four cycles of R-HCVAD alternating with methotrexate-cytarabine (part B) were administered. If they did not have a complete response or had a partial response, patients received two cycles of R-HCVAD alternating with methotrexate-cytarabine followed by reassessment, up to a total of eight cycles. Patients were taken off study if they had stable disease or progression during R-HCVAD. The primary outcome was the overall response rate after part A. The analyses were conducted on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, number NCT02427620. FINDINGS: 131 patients were enrolled between June 12, 2015, and Dec 6, 2018. The median age was 56 years (IQR 49-60). 58 (50%) of 117 patients had high Ki-67 (≥30%). 129 (98%, 95% CI 95-100) of 131 patients had an overall response in part A. The most common grade 3-4 adverse events were lymphocytopenia (19 [14%] of 131), skin rash (16 [12%]), thrombocytopenia (12 [9%]), infections (11 [8%]), and fatigue (ten [8%]) in part A and lymphocytopenia (96 [73%]), leukocytopenia (42 [32%]), thrombocytopenia (40 [30%]), and neutropenia (26 [20%]) in part B. There was one on-study death, which was not deemed to be treatment-related. INTERPRETATION: Induction with ibrutinib-rituximab in the frontline treatment of young patients with mantle cell lymphoma is active and safe. This approach allowed minimisation of the number of chemotherapy cycles, thereby reducing the adverse events associated with chemotherapy. Newer trials bringing the next-generation Bruton's tyrosine kinase inhibitors into the frontline setting might obviate the need for chemotherapy altogether in patients with mantle cell lymphoma. FUNDING: Pharmacyclics, Janssen.

Clinicopathologic spectrum of myeloid neoplasms with concurrent myeloproliferative neoplasm driver mutations and SRSF2 mutations.

Myeloproliferative neoplasms (MPNs) are frequently associated with classic driver mutations involving JAK2, MPL or CALR. SRSF2 is among the most frequently mutated splicing genes in myeloid neoplasms and SRSF2 mutations are known to confer a poor prognosis in patients with MPNs. In this study, we sought to evaluate the clinicopathologic spectrum of myeloid neoplasms harboring concurrent MPN-driver mutations and SRSF2 mutations. The study cohort included 27 patients, 22 (82%) men and five (19%) women, with a median age of 71 years (range, 51-84). These patients presented commonly with organomegaly (n = 15; 56%), monocytosis (n = 13; 48%), morphologic dysplasia (n = 11; 41%), megakaryocytic hyperplasia and/or clustering (n = 10; 37%) and bone marrow fibrosis >MF-1 (17/22; 77%). About one third of patients either initially presented with acute myeloid leukemia (AML) or eventually progressed to AML. Eighteen (68%) patients had a dominant clone with SRSF2 mutation and nine (33%) patients had a dominant clone with a classic MPN-associated driver mutation. Our data suggest that the presence of an SRSF2 mutation preceding the acquisition of a MPN driver mutations is not a disease-defining alteration nor is it restricted to any specific disease entity within the spectrum of myeloid neoplasms. In summary, patients with myeloid neoplasms associated with concurrent SRSF2 and classic MPN driver mutations have clinical and morphologic features close to that of classic MPNs often with frequent dysplasia and monocytosis.

Immunohistochemical loss of enhancer of Zeste Homolog 2 (EZH2) protein expression correlates with EZH2 alterations and portends a worse outcome in myelodysplastic syndromes.

EZH2 coding mutation (EZH2MUT), resulting in loss-of-function, is an independent predictor of overall survival in MDS. EZH2 function can be altered by other mechanisms including copy number changes, and mutations in other genes and non-coding regions of EZH2. Assessment of EZH2 protein can identify alterations of EZH2 function missed by mutation assessment alone. Precise evaluation of EZH2 function and gene-protein correlation in clinical MDS cohorts is important in the context of upcoming targeted therapies aimed to restore EZH2 function. In this study, we evaluated the clinicopathologic characteristics of newly diagnosed MDS patients with EZH2MUT and correlated the findings with protein expression using immunohistochemistry. There were 40 (~6%) EZH2MUT MDS [33 men, seven women; median age 74 years (range, 55-90)]. EZH2 mutations spanned the entire coding region. Majority had dominant EZH2 clone [median VAF, 30% (1-92)], frequently co-occurring with co-dominant TET2 (38%) and sub-clonal ASXL1 (55%) and RUNX1 (43%) mutations. EZH2MUT MDS showed frequent loss-of-expression compared to EZH2WT (69% vs. 27%, p = 0.001). Interestingly, NINE (23%) EZH2WT MDS also showed loss-of-expression. EZH2MUT and loss-of-expression significantly associated with male predominance and chr(7) loss. Further, only EZH2 loss-of-expression patients showed significantly lower platelet counts, a trend for higher BM blast% and R-IPSS scores. Over a 14-month median follow-up, both EZH2MUT (p = 0.027) and loss-of-expression (p = 0.0063) correlated with poor survival, independent of R-IPSS, age and gender. When analyzed together, loss-of-expression showed a stronger correlation than mutation (p = 0.061 vs. p = 0.43). In conclusion, immunohistochemical assessment of EZH2 protein, alongside mutation, is important for prognostic workup of MDS.

EZH2 expression is associated with inferior overall survival in mantle cell lymphoma.

Enhancer of zeste homolog 2 (EZH2) is a catalytic component of the polycomb repressive complex 2 (PRC2) which reduces gene expression via trimethylation of a lysine residue of histone 3 (H3K27me3). Expression of EZH2 has not been assessed systematically in mantle cell lymphoma (MCL). Expression of EZH2 was assessed by immunohistochemistry in 166 patients with MCL. We also assessed other PRC2 components and H3K27me3. Fifty-seven (38%) of MCL patients were positive for EZH2 using 40% cutoff. EZH2 expression was associated with aggressive histologic variants (65% vs. 29%, p < 0.001), high Ki-67 proliferation rate (median, 72% vs. 19%, p < 0.001), and p53 overexpression (43% vs. 2%, p < 0.001). EZH2 expression did not correlate with expression of other PRC2 components (EED and SUZ12), H3K27me3, MHC-I, and MHC-II. Patients with EZH2 expression (EZH2+) had a poorer overall survival (OS) compared with patients without EZH2 expression (EZH2-) (median OS: 3.9 years versus 9.4 years, respectively, p < 0.001). EZH2 expression also predicted a poorer prognosis in MCL patients with classic histology (median OS, 4.6 years for EZH2+ and 9.6 years for EZH2-negative, respectively, p < 0.001) as well as aggressive histology (median OS, 3.7 years for EZH2+ and 7.9 years for EZH2-negative, respectively, p = 0.046). However, EZH2 expression did not independently correlate with overall survival in a multivariate analysis. Gene expression analysis and pathway enrichment analysis demonstrated a significant enrichment in cell cycle and mitotic transition pathways in MCL with EZH2 expression. EZH2 expression detected by immunohistochemistry is present in 38% of MCL cases and it is associated with high proliferation rate, p53 overexpression, aggressive histologic variants, and poorer OS. Based on gene expression profiling data, EZH2 expression could potentiate cell cycle machinery in MCL. These data suggest that assessment of EZH2 expression could be useful to stratify MCL patients into low- and high-risk groups.

Chronic myeloid neoplasms harboring concomitant mutations in myeloproliferative neoplasm driver genes (JAK2/MPL/CALR) and SF3B1.

JAK2, CALR, and MPL are myeloproliferative neoplasm (MPN)-driver mutations, whereas SF3B1 is strongly associated with ring sideroblasts (RS) in myelodysplastic syndrome (MDS). Concomitant mutations of SF3B1 and MPN-driver mutations out of the context of MDS/MPN with RS and thrombocytosis (MDS/MPN-RS-T) are not well-studied. From the cases (<5% blasts) tested by NGS panels interrogating at least 42 myeloid neoplasm-related genes, we identified 18 MDS/MPN-RS-T, 42 MPN, 10 MDS, and 6 MDS/MPN-U cases with an SF3B1 and an MPN-driver mutation. Using a 10% VAF difference to define "SF3B1-dominant," "MPN-mutation dominant," and "no dominance," the majority of MDS/MPN-RS-T clustered in "SF3B1-dominant" and "no dominance" regions. Aside from parameters as thrombocytosis and ≥15% RS required for RS-T, MDS also differed in frequent neutropenia, multilineage dysplasia, and notably more cases with <10% VAF of MPN-driver mutations (60%, p = 0.0346); MPN differed in more frequent splenomegaly, myelofibrosis, and higher VAF of "MPN-driver mutations." "Gray zone" cases with features overlapping MDS/MPN-RS-T were observed in over one-thirds of non-RS-T cases. This study shows that concomitant SF3B1 and MPN-driver mutations can be observed in MDS, MPN, and MDS/MPN-U, each showing overlapping but also distinctively different clinicopathological features. Clonal hierarchy, cytogenetic abnormalities, and additional somatic mutations may in part contribute to different disease phenotypes, which may help in the classification of "gray zone" cases.

Clinical, immunophenotypic and genomic findings of NK lymphoblastic leukemia: a study from the Bone Marrow Pathology Group.

Natural killer (NK) cells are lymphocytes of the native immune system that play a pivotal role in host defense and immune surveillance. While the conceptual view of NK-neoplasms is evolving, little is known about the rare NK lymphoblastic leukemia (NK-LL), which remains as a provisional entity in the 2016 WHO Classification. The goal of this study is to characterize NK-LL cases and compare with other CD56 co-expressing acute leukemias. We identified 105 cases, diagnosed as NK-LL (6), CD56+ acute undifferentiated leukemia (AUL) (6), CD56+ T-lymphoblastic leukemia (T-LL) (51), and CD56+ acute myeloid leukemia (AML) (42). Compared to AUL patients, NK-LL patients were significantly younger (p = 0.021) and presented with higher white blood cell (WBC) (p = 0.037) and platelet counts (p = 0.041). Flow cytometry showed more frequent expression of cytoplasmic CD3 (cCD3, p = 0.064) and CD33, (p = 0.065), while HLA-DR was significantly absent from NK-LL (p = 0.035) compared to AUL. Compared to T-ALL, NK-LL cases showed less frequent cCD3 (p = 0.002), CD4 (p = 0.051), and CD10 expression (p = 0.06). The frequency of abnormal karyotypes was similar between NK-LL, AUL, and T-ALL. The mutational profile differed in four leukemia groups, with a significance enrichment of NOTCH1 (p = 0.002), ETV6 (p = 0.002) and JAK3 (p = 0.02) mutations in NK-LL as compared to AML. As compared to T-ALL, NK-LL cases showed a higher number of total mutations (p = 0.04) and significantly more frequent ETV6 mutations (p = 0.004). Clinical outcome data showed differences in overall survival between all four groups (p = 0.0175), but no difference in event free survival (p = 0.246). In this largest study to date, we find that that NK-LL shows clinical presentation, immunophenotypic and molecular characteristics distinct from AUL, T-ALL, and AML. Our findings suggest NK-LL is a distinct acute leukemia entity and should be considered in the clinical diagnosis of acute leukemias of ambiguous lineage.

Breast implant-associated anaplastic large cell lymphoma: clinical follow-up and analysis of sequential pathologic specimens of untreated patients shows persistent or progressive disease.

Breast implant-associated anaplastic large cell lymphoma (ALCL) is a distinctive type of T-cell lymphoma that arises around textured-surface breast implants. In a subset of patients, this disease can involve surrounding tissues, spread to regional lymph nodes, and rarely metastasize to distant sites. The aim of this study was to assess sequential pathologic specimens from patients with breast implant-associated ALCL to better understand the natural history of early-stage disease. To achieve this goal, we searched our files for patients who had breast implant-associated ALCL and who had undergone earlier surgical intervention with assessment of biopsy or cytologic specimens. We then focused on the patient subset in whom a definitive diagnosis was not established, and patients did not receive current standard-of-care therapy at that time. We identified a study group of ten patients with breast implant-associated ALCL in whom pathologic specimens were collected 0.5 to 4 years before a definitive diagnosis was established. A comparison of these serial biopsy specimens showed persistent disease without change in pathologic stage in three patients, progression in five patients, and persistence versus progression in two patients. Eventually, six patients underwent implant removal with complete capsulectomy and four underwent partial capsulectomy. Seven patients also received chemotherapy because of invasive disease, three of whom also received radiation therapy, two brentuximab vedotin after chemotherapy failure, and one allogeneic stem cell transplant. Eight patients achieved complete remission and two had partial remission after definitive therapy. At time of last follow-up, six patients were alive without disease, one had evidence of disease, one died of disease, and two patients died of unrelated cancers. In summary, this analysis of sequential specimens from patients with breast implant-associated ALCL suggests these neoplasms persist or progress over time if not treated with standard-of-care therapy.

Efficacy of venetoclax in high risk relapsed mantle cell lymphoma (MCL) - outcomes and mutation profile from venetoclax resistant MCL patients.

Venetoclax is effective in relapsed patients with mantle cell lymphoma (MCL). Mechanisms of resistance to venetoclax in MCL are poorly understood. We describe the clinical outcomes and genomic characteristics of 24 multiply relapsed patients (median of five prior lines of therapy) who received venetoclax-based therapies; 67% had progressed on BTK inhibitors (BTKi) and 54% had blastoid or pleomorphic histology. Median follow up after venetoclax treatment was 17 months. The overall response rate was 50% and complete response (CR) rate was 21%, 16 patients had progressed and 15 died. The median progression free, overall and post venetoclax survival were 8, 13.5 and 7.3 months respectively. Whole-exome sequencing (WES) was performed on samples collected from seven patients (including five pairs; before starting venetoclax and after progression on venetoclax). The SMARCA4 and BCL2 alterations were noted only after progression, while TP53, CDKN2A, KMT2D, CELSR3, CCND1, NOTCH2 and ATM were altered 2-4-fold more frequently after progression. In two patients with serial samples, we demonstrated clonal evolution of novel SMARCA4 and KMT2C/D mutations at progression. Mutation dynamics in venetoclax resistant MCL is demonstrated. Our data indicates that venetoclax resistance in MCL is predominantly associated with non-BCL2 gene mutations. Further studies are ongoing in MCL patients to evaluate the efficacy of venetoclax in combination with other agents and understand the biology of venetoclax resistance in MCL.

High-grade B-cell lymphomas with TdT expression: a diagnostic and classification dilemma.

Mature B-cell neoplasms and immature or precursor B-cell neoplasms need to be distinguished because these patients usually require different therapeutic approaches. B-cell neoplasms that express TdT without unequivocal other features of immaturity may therefore present a diagnostic challenge. We describe 13 patients with TdT-positive aggressive B-cell lymphoma. The clinicopathologic features of these patients were highly heterogeneous, but for the purpose of this study we grouped these cases as follows: (1) de novo high-grade B-cell lymphoma with MYC, BCL2, and/or BCL6 rearrangements (double-hit or triple-hit lymphoma) with TdT expression. In this group we included two cases of de novo composite lymphoma in which there were components of diffuse large B-cell lymphoma and TdT-positive blastic B-cell lymphoma; (2) TdT-positive aggressive B-cell lymphoma arising in patients who previously had follicular lymphoma; (3) initial relapse of TdT-negative aggressive B-cell lymphoma in patients who previously had follicular lymphoma, followed by relapses in which the neoplasm acquired TdT expression; and (4) mature B-cell lymphomas that acquired TdT expression at relapse. This group included one case of EBV-positive diffuse large B-cell lymphoma and one case of pleomorphic variant mantle cell lymphoma. All patients in this study had an aggressive clinical course and a dismal outcome despite appropriate therapy. Rather than "squeezing" these cases into current World Health Organization classification categories, we suggest the use of a descriptive term such as high-grade B-cell lymphoma with TdT expression. In these tumors, the cytogenetic findings and poor prognosis of this patient subgroup suggest that these neoplasms need to be distinguished from B-lymphoblastic leukemia/lymphoma. Segregation of these neoplasms also may foster additional research on these neoplasms.

Clinical, immunophenotypic, and genomic findings of acute undifferentiated leukemia and comparison to acute myeloid leukemia with minimal differentiation: a study from the bone marrow pathology group.

Acute undifferentiated leukemia is a rare type of acute leukemia that shows no evidence of differentiation along any lineage. Clinical, immunophenotypic and genetic data is limited and it is uncertain if acute undifferentiated leukemia is biologically distinct from acute myeloid leukemia with minimal differentiation, which also shows limited myeloid marker expression and has been reported to have a poor prognosis. We identified 92 cases initially diagnosed as acute undifferentiated leukemia or acute myeloid leukemia with minimal differentiation from pathology databases of nine academic institutions with available diagnostic flow cytometric data, cytogenetic findings, mutational and clinical data. Outcome analysis was performed using Kaplan Meier test for the 53 patients who received induction chemotherapy. Based on cytogenetic abnormalities (N = 30) or history of myelodysplastic syndrome (N = 2), 32 cases were re-classified as acute myeloid leukemia with myelodysplasia related changes. The remaining 24 acute undifferentiated leukemia patients presented with similar age, blood counts, bone marrow cellularity, and blast percentage as the remaining 30 acute myeloid leukemia with minimal differentiation patients. Compared to acute myeloid leukemia with minimal differentiation, acute undifferentiated leukemia cases were characterized by more frequent mutations in PHF6 (5/15 vs 0/19, p = 0.016) and more frequent expression of TdT on blasts (p = 0.003) while acute myeloid leukemia with minimal differentiation cases had more frequent CD123 expression (p = 0.042). Outcome data showed no difference in overall survival, relapse free survival, or rates of complete remission between acute undifferentiated leukemia and acute myeloid leukemia with minimal differentiation groups (p > 0.05). Acute myeloid leukemia with myelodysplasia-related changes patients showed shorter survival when censoring for bone marrow transplant as compared to acute undifferentiated leukemia (p = 0.03) and acute myeloid leukemia with minimal differentiation (p = 0.002). In this largest series to date, the acute undifferentiated leukemia group shows distinct characteristics from acute myeloid leukemia with minimal differentiation, including more frequent PHF6 mutations and expression of TdT.

Persistent IDH1/2 mutations in remission can predict relapse in patients with acute myeloid leukemia.

Persistence of IDH1 or IDH2 mutations in remission bone marrow specimens of patients with acute myeloid leukemia has been observed, but the clinical impact of these mutations is not well known. In this study, we evaluated 80 acute myeloid leukemia patients with known IDH1 R132 or IDH2 R140/R172 mutations and assessed their bone marrow at the time of remission to determine the potential impact of persistent IDH1/2 mutations. Approximately 40% of acute myeloid leukemia patients given standard treatment in this cohort had persistent mutations in IDH1/2 Patients with an IDH1/2 mutation had an increased risk of relapse after 1 year of follow-up compared to patients without a detectable IDH1/2 mutation (59% versus 24%; P<0.01). However, a persistent mutation was not associated with a shorter time to relapse. High IDH1/2 mutation burden (mutant allelic frequency ≥10%) did not correlate with relapse rate (77% versus 86% for patients with a low burden, i.e., mutant allelic frequency <10%; P=0.66). Persistent mutations were also observed in NPM1, DNMT3A and FLT3 during remission, but IDH1/2 mutations remained significant in predicting relapse by multivariate analysis. Flow cytometry was comparable and complementary to next-generation sequencing-based assay for predicting relapse. Monitoring for persistent IDH1/2 mutations in patients with acute myeloid leukemia in remission can provide information that could be used to justify early interventions, with the hope of facilitating longer remissions and better outcomes in these patients.

American Registry of Pathology Expert Opinions: Immunohistochemical evaluation of classic Hodgkin lymphoma.

The diagnosis of classic Hodgkin lymphoma requires immunohistochemical confirmation in most cases and one can argue for these studies as standard-of-care in the diagnostic workup. The authors propose a panel of studies for primary identification of CHL to include: CD3, CD20, CD15, CD30 and PAX5. When pattern discordances are identified, additional assessment is recommended. In the case of overexpression of B lineage markers by Hodgkin/Reed-Sternberg cells, or a differential diagnosis that includes large B-cell lymphoma or variants, additional markers recommended are: CD45, OCT2, BOB1, CD79a and MUM1/IRF4. If primary mediastinal large B cell lymphoma is considered in the differential diagnosis, suggested additional markers include: P63, CD23, CD45 and CD79a. When considering a differential diagnosis that includes anaplastic large cell lymphoma we suggest: ALK, CD45, pan T cell antigens (such as CD2, CD5, CD7, and CD43), and cytotoxic markers (granzyme, perforin, and TIA1). If peripheral T cell lymphoma or T cell lymphomas of follicular helper origin are considered in the differential diagnosis, the following panel is recommended: pan T cell antigens, CD4, CD8, one or more follicular dendritic cell markers, and assessment for Epstein-Barr virus (EBV) infection, preferably EBV encoded RNA (EBER) as assessed by in situ hybridization When the differential diagnosis includes nodular lymphocyte predominant Hodgkin lymphoma, recommended additional studies include OCT2, CD21 and/or CD23, PD1, and assessment for EBV infection. The authors recognize that these panels may not be adequate to completely characterize other lymphomas, but these panels will usually be sufficient to distinguish classic Hodgkin lymphoma from other lymphoma types.

TP53 mutations are common in mantle cell lymphoma, including the indolent leukemic non-nodal variant.

INTRODUCTION: Mantle cell lymphoma (MCL) is an aggressive B-cell neoplasm, but clinically indolent subtypes are also recognized. Data on the utility of mutation profiling in the context of routine workup and its role in risk-stratification of MCL patients are limited. In this study, we describe the mutational landscape and clinicopathologic correlates of a series of MCL cases at a single-institution setting. METHODS: Samples from 26 patients with MCL were evaluated by NGS using DNA extracted from peripheral blood (PB) or bone marrow (BM). Evaluation of extent of PB or BM involvement was performed using flow cytometry immunophenotyping. RESULTS: The study group included 17 (65%) men and 9 (35%) women with a median age of 65 years (range, 50-94). Twenty-one (81%) patients had nodal MCL (N-MCL) and 5 (19%) had the "leukemic variant" (L-MCL). Mutated genesincluded TP53 (35%), ATM (27%), CARD11 (10%); and FBXW7, NOTCH1, SPEN, BIRC3 (~5% each). Most mutations were clonal in nature. Ten unique TP53 mutations were identified in 9 samples, including 3 L-MCL cases. There was no difference in the frequency of TP53 mutations between L-MCL and N-MCL groups (p = 0.3), but TP53 mutations were subclonal in 2/3 L-MCL cases. Identification of clonal TP53 alterations in L-MCL patients prompted initiation of therapy despite low tumor burden. CONCLUSIONS: TP53 is commonly mutated in MCL. TP53 mutations may be clonal or subclonal. Seemingly indolent L-MCL may harbor subclonal TP53 mutations which may serve as a useful biomarker for prognostication, therapeutic planning, follow-up monitoring, and early detection of clonal expansion.