Mutations of CCAAT/enhancer–binding protein alpha (CEBPAmu) are found in 10% to 15% of de novo acute myeloid leukemia (AML) cases. Double-mutated CEBPA (CEBPAdm) is associated with a favorable prognosis; however, single-mutated CEBPA (CEBPAsm) does not seem to improve prognosis. We investigated CEBPAmu for prognosis in 1028 patients with AML, registered in the Multi-center Collaborative Program for Gene Sequencing of Japanese AML. It was found that CEBPAmu in the basic leucine zipper domain (bZIP) was strongly associated with a favorable prognosis, but CEBPAmu out of the bZIP domain was not. The presence of CEBPAmu in bZIP was a strong indicator of a higher chance of achieving complete remission (P < .001), better overall survival (OS; P < .001) and a lower risk of relapse (P < .001). The prognostic significance of CEBPAmu in bZIP was also observed in the subgroup with CEBPAsm (all patients: OS, P = .008; the cumulative incidence of relapse, P = .063; patients aged ≤70 years and with intermediate-risk karyotype: OS, P = .008; cumulative incidence of relapse, P = .026). Multivariate analysis of 744 patients aged ≤70 years showed that CEBPAmu in bZIP was the most potent predictor of OS (hazard ratio, 0.3287; P < .001). CEBPAdm was validated as a cofounding factor, which was overlapping with CEBPAmu in bZIP. In summary, these findings indicate that CEBPAmu in bZIP is a potent marker for AML prognosis. It holds potential in the refinement of treatment stratification and the development of targeted therapeutic approaches in CEBPA-mutated AML.

Nucleophosmin1 (NPM1) mutations are the most frequently detected gene mutations in acute myeloid leukemia (AML) and are considered a favorable prognostic factor. We retrospectively analyzed the prognosis of 605 Japanese patients with de novo AML, including 174 patients with NPM1‐mutated AML. Although patients with NPM1‐mutated AML showed a high remission rate, this was not a favorable prognostic factor for overall survival (OS); this is contrary to generally accepted guidelines. Comprehensive gene mutation analysis showed that mutations in codon R882 of DNA methyltransferase 3A (DNMT3A^R882 mutations) were a strong predicative factor indicating poor prognosis in all AML (p < 0.0001) and NPM1‐mutated AML cases (p = 0.0020). Furthermore, multivariate analysis of all AML cases showed that DNMT3A^R882 mutations and the co‐occurrence of internal tandem duplication in FMS‐like tyrosine kinase 3 (FLT3‐ITD), NPM1 mutations, and DNMT3A^R882 mutations (triple mutations) were independent factors predicting a poor prognosis related to OS, with NPM1 mutations being an independent factor for a favorable prognosis (hazard ratios: DNMT3A^R882 mutations, 1.946; triple mutations, 1.992, NPM1 mutations, 0.548). Considering the effects of DNMT3A^R882 mutations and triple mutations on prognosis and according to the classification of NPM1‐mutated AML into three risk groups based on DNMT3A^R882/FLT3‐ITD genotypes, we achieved the improved stratification of prognosis (p < 0.0001). We showed that DNMT3A^R882 mutations are an independent factor for poor prognosis; moreover, when confounding factors that include DNMT3A^R882 mutations were excluded, NPM1 mutations were a favorable prognostic factor. This revealed that ethnological prognostic discrepancies in NPM1 mutations might be corrected through prognostic stratification based on the DNMT3A status.

What is known and objective 5‐Azacitidine (AZA) is an agent widely used to treat myelodysplastic syndrome (MDS). Case description We herein report an 83‐year‐old woman diagnosed with MDS who was treated with AZA. She tolerated the first cycle of AZA; however, severe adverse events involving haemorrhagic enteritis with multiple intestinal ulcers developed after the second and third cycles. Additionally, the interval between the administration of AZA and the development of haematochezia shortened with each cycle of AZA. What is new and Conclusion We herein report as‐yet‐undescribed potential side effects, AZA‐associated haemorrhagic enteritis that should be kept in mind.

Background and Clinical Significance: Mantle cell lymphoma (MCL) frequently involves bone marrow, gastrointestinal tract, and hepatosplenomegaly, whereas pleural effusions are uncommon. Cases requiring invasive mechanical ventilation and thoracic drainage are rare. We report a case of MCL with persistent massive pleural effusions requiring invasive mechanical ventilation and bilateral continuous thoracic drainage. Case Presentation: A 71-year-old woman presented with dyspnea and was found to have bilateral pleural effusions and generalized lymphadenopathy. Shortly after admission, she developed acute respiratory failure due to pleural effusions and required invasive mechanical ventilation. Right-sided continuous thoracic drainage was initiated. Thereafter, more than 1 L of pleural fluid was drained each day. Flow cytometry of the pleural fluid showed CD5-positive B cells with kappa light-chain restriction. Bone marrow examination revealed abnormal lymphocyte infiltration. Cervical lymph node biopsy demonstrated diffuse proliferation of medium-sized, abnormal B lymphocytes with an immunophenotype of CD5⁺, CD19⁺, CD20⁺, cyclin D1⁺, SOX11⁺, and κ⁺, with a Ki-67 index of 20%, confirming MCL, stage IV. Immunochemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) was commenced under mechanical ventilation. Shortly thereafter, left-sided continuous thoracic drainage was also initiated. However, in response to immunochemotherapy, the bilateral pleural effusions gradually subsided, enabling extubation, and there was no reaccumulation after removal of both chest tubes. Furthermore, generalized lymphadenopathy regressed, and bone marrow examination revealed resolution of lymphoma infiltration, resulting in complete remission. Conclusions: De novo MCL complicated by persistent massive pleural effusions requiring invasive mechanical ventilation and bilateral continuous thoracic drainage is rare. A thorough diagnostic workup followed by prompt initiation of immunochemotherapy can arrest pleural output, enable extubation, and be lifesaving. Clinicians should recognize that MCL rarely presents with persistent massive pleural effusions.