Clinicopathologic and Molecular Analysis of Normal Karyotype Therapy-Related and De Novo Acute Myeloid Leukemia: A Multi-Institutional Study by the Bone Marrow Pathology Group.

PURPOSE: Therapy-related acute myeloid leukemias (t-AML) are a heterogenous group of aggressive neoplasms that arise following exposure to cytotoxic chemotherapy and/or ionizing radiation. Many therapy-related myeloid neoplasms (t-MN) are associated with distinct chromosomal aberrations and/or TP53 alterations, but little is known about the clinicopathologic and molecular features of normal karyotype t-AML (NK-t-AML) and whether this t-MN subtype is distinctly different from NK de novo AML (NK-dn-AML). METHODS: This multi-institutional study by the Bone Marrow Pathology Group retrospectively evaluated clinicopathologic and molecular characteristics of 335 patients with NK-AML, comprising 105 t-AML and 230 dn-AML cases. RESULTS: Patients with t-AML compared with dn-AML exhibit significantly shorter overall survival (OS; median months: 17.6 v 44.2; P < .0001) and relapse-free survival (RFS; median months: 9.1 v 19.2; P = .0018). Frequency of NPM1, FLT3, KRAS, and GATA2 mutations were significantly different in NK-t-AML compared with NK-dn-AML (NPM1 35% v 49%; P = .0493; FLT3 23% v 36%; P = 0494; KRAS 12% v 5%; P = .0465; GATA2 9% v 2% P = .0105), while TP53 mutations were rare. Patients with t-AML more often stratified into intermediate or adverse 2017 ELN genetic risk groups. Favorable ELN risk predicted favorable OS (hazard ratio [HR], 0.4056; 95% CI, 0 to 0.866; P = .020) and RFS (HR, 0.355; 95% CI, 0 to 0.746; P = .006). Among all patients with NK-AML, stem-cell transplant and favorable ELN risk both significantly affected RFS, while therapy-relatedness and age had a borderline significant impact on OS (HR, 1.355; 95% CI, 0.975 to 1.882; P = .070). CONCLUSION: To our knowledge, this is the largest study to date to comprehensively evaluate NK-t-AML and provides a framework that may inform our understanding of NK-t-AML disease biology and could potentially help guide therapeutic management and improved disease classification in t-MNs that lack cytogenetic aberrations.

How I investigate acquired megaloblastic anemia.

In this review of megaloblastic anemia (MA), an overview of vitamin B12 and folate body requirements, biochemical pathways, and laboratory testing strategies will be provided. However, the focus of this review is the classic and unique features of MA in blood and bone marrow. Acquired MA is a benign disorder for many, but can be detrimental for some. The clinical presentation can vary considerably, and the spectrum of symptoms and signs is diverse and quite broad. Prompt recognition and therapy are critical to prevent potential irreversible damage and clinical sequelae, especially in patients with vitamin B12 deficiency. A delay in diagnosis of vitamin B12 deficiency can result in significant neurologic sequelae that may not fully resolve with treatment, including in neonates and young infants. The blood and bone marrow features in MA can closely mimic thrombocytopenic purpura, myelodysplasia, and other myeloid neoplasms. Both pancytopenia and normal MCV at presentation are common in MA and raise unique challenges for the diagnostician. Partially treated MA is also a significant diagnostic "trap". MA is highly responsive to treatment, and patients tend to improve rapidly upon treatment initiation. However, the broad range of clinical and hematologic features makes the rapid, successful diagnosis of MA a unique challenge for the hematopathologist. Even in the era of state-of-the-art laboratory testing, a high suspicion is required.

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.

Up-regulation of Flotillin-2 is associated with melanoma progression and modulates expression of the thrombin receptor protease activated receptor 1.

Flotillin 2 (flot-2) is a highly conserved protein isolated from caveolae/lipid raft domains that tether growth factor receptors linked to signal transduction pathways. Flot-2 protein and mRNA were increased in tumorigenic and metastatic melanoma cell lines in vitro, and the immunostaining intensity increased substantially across a tissue array of melanocytic lesions. Flot-2 transfection transformed SB2 melanoma cells from nontumorigenic, nonmetastatic to highly tumorigenic and metastatic in a nude mouse xenograft model. SB2 cells stably transfected with the flot-2 cDNA (SB2-flot)-2 cells proliferated faster in the absence of serum, and their migration through Matrigel was additionally enhanced by thrombin. When SB2-flot-2 cells were compared with SB2-vector-control cells on a cancer gene pathway array, SB2-flot-2 cells had increased expression of protease activated receptor 1 (PAR-1) mRNA, a transmembrane, G-protein-coupled receptor involved in melanoma progression. PAR-1 and flot-2 were coimmunoprecipitated from SB2-flot-2 cells. Up-regulation of PAR-1 was additionally confirmed in SB2-flot-2 cells and melanoma cell lines. SB2-flot-2 cells transfected with flot-2-specific small-interfering RNAs made substantially less flot-2 and PAR-1 mRNA. In conclusion, flot-2 overexpression is associated with melanoma progression, with increased PAR-1 expression, and with transformation of SB2 melanoma cells to a highly metastatic line. Flot-2 binds to PAR-1, a known upstream mediator of major signal transduction pathways implicated in cell growth and metastasis, and may thereby influence tumor progression.