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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.The authors assessed the clinicopathologic and molecular genetic features of 80 ETNK1-mutated myeloid neoplasms.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.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.

Comprehensive investigation of CD8+ T cells in acute myeloid leukemia (AML) is essential for developing immunotherapeutic strategies beyond immune checkpoint blockade. Herein, we performed single-cell RNA profiling of CD8+ T cells from 3 healthy bone marrow donors and 23 newly diagnosed (NewlyDx) and 8 relapsed/refractory (RelRef) AML patients. Cells co-expressing canonical exhaustion markers formed a cluster constituting

Activating mutations in the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway have been shown in nearly half of the cases of Rosai-Dorfman disease (RDD). Cyclin D1, a key cell cycle regulator, constitutes a major downstream target of the MAPK/ERK pathway. In this study, we aim to further understand the pathogenesis of RDD by assessing the lesional histiocytes for cyclin D1, p-ERK, Ki-67, and BCL-2 by immunohistochemistry. We assessed 35 samples of RDD and a control group of histiocyte-rich reactive lesions. Cyclin D1 was expressed in about 90% of cases of RDD. Cyclin D1 was positive in 25-95% (median, 85%) of lesional histiocytes, was moderately/strongly expressed in 97% of cyclin D1-positive cases, and was significantly higher than in control specimens. p-ERK was positive in 16 of 30 (53%) cases of RDD and was negative in all controls. All p-ERK-positive RDD cases had concurrent cyclin D1 expression, whereas more than a third of cyclin D1-positive cases were negative for p-ERK. Ki-67 was low in RDD (median, 3%). BCL-2 was positive in lesional histiocytes in nine of 10 RDD cases assessed. Overall, these findings point to unexpected, potential roles of these molecules in the pathogenesis of RDD. Overexpression of cyclin D1 in the absence of ERK phosphorylation in a subset of RDD cases opens the possibility of oncogenic mechanisms bypassing ERK and supports the notion that cyclin D1 overexpression in RDD is multifactorial. Moreover, the observed lack of correlation between cyclin D1 with Ki-67 proliferative index suggests that prosurvival actions of cyclin D1 are, at least in part, cell cycle independent. Finally, expression of BCL-2 and the low Ki-67 index suggest that RDD might be driven by antiapoptotic rather than proproliferative oncogenic mechanisms.

High-throughput genomic analysis of plasma cell myeloma has identified recurrent gene mutations of prognostic significance. Mutations in the RAS-MAPK pathway, such as KRAS, NRAS, and BRAF, are known as high-risk factors associated with poor prognosis in patients with various types of cancers, but studies in myeloma have yielded mixed results. We describe the clinicopathologic, cytogenetic, molecular features and outcomes of 68 patients with RAS/BRAF-mutated myeloma, and compare this group with 79 myeloma patients without any mutations. We show that KRAS, NRAS and BRAF were mutated in 16%, 11%, and 5% of cases, respectively. The RAS/BRAF-mutated group included 39 men and 29 women with a median age of 63 years (range, 35–82) at initial diagnosis. Patients with RAS/BRAF-mutated myeloma had lower hemoglobin and platelet counts, higher levels of serum lactate dehydrogenase and calcium, higher percentage of bone marrow plasma cells, and more advanced R-ISS stage. In addition, RAS/BRAF mutations were associated with complex karyotype and extra copies of CKS1B. The median overall survival and progression-free survival were significantly shorter for patients in the RAS/BRAF-mutated group (69.0 months vs 220.7 months, p = 0.0023 and 46.0 months vs 60.6 months, p = 0.0311, respectively). Univariate analysis revealed that KRAS mutation, NRAS mutation, lower hemoglobin level, elevated lactate dehydrogenase, higher R-ISS stage, complex karyotype, gain/amplification of CKS1B, monosomy 13/RB1 deletion and lack of autologous stem cell transplantation were associated with poorer prognosis. Multivariate analysis showed that KRAS mutation, lower hemoglobin level, higher level of serum calcium, higher ISS stage and lack of autologous stem cell transplantation predict inferior outcome. In summary, RAS/BRAF mutations occur in 30–40% of myeloma cases and are associated with higher tumor burden, higher R-ISS stage, complex karyotype, and shorter overall survival and progression-free survival. These findings support testing for RAS/BRAF mutations in myeloma patients and underscore the potential therapeutic benefits of RAS/BRAF inhibitors.

Acute Myeloid Leukemia (AML) is a heterogenous disease characterized by immature blasts at different states of differentiation resulting in marked intra-tumor heterogeneity (ITH). Compared to patients with diploid cytogenetics, deletions in chromosome 7/7q (del7/7q), 5/5q (del5/5q) or double deletion (del5/5q & del 7/7q) confer worse outcomes in AML. We conducted single cell RNA (scRNA) profiling of bone marrow mononulear cells (BMMCs) from 20 newly diagnosed adult AML patients with diploid (n=7), del5/5q (n=5), del7/7q (n=5) and double deletion (n=3) to uncover ITH within each group and reveal cellular hierarchies associated with inferred copy number variations (CNV). Diffusion map analysis revealed heterogenous gene expression pattern in AML cells of del7/7q and double deletion patients, compared to diploid and del5/5q patients. CNV-based subgrouping of AML cells revealed significant enrichment of antigen presentation and immune response pathways in cells with inferred del7/7q or double deletion compared to cells without these deletions in the same patients, suggesting a heterogenous immune state in AML cells correlating with inferred genomic copy numbers. To dissect the composition of cellular hierarchies, AML cells were then projected onto an independent healthy BMMC reference (&gt20,000 cells) and labeled based on transcriptional similarity to healthy hematopoietic cells. AML cells from diploid patients were enriched for GMP-like and monocyte-like cells, while cells from non-diploid patients were enriched in more primitive states (HSC-like and CMP/LMPP-like). Correlating these hierarchal groups with leukemic stem cell (LSC) hierarchies revealed shared transcriptional program in LSC-like states across HSC-like, GMP-like, CLP-like and erythroid-like cells. This suggests that LSC signatures can also be expressed across AML cells and not just primitive cells. These findings were also validated in deconvolution analysis of bulk transcriptomes from three independent newly diagnosed AML cohorts (TCGA, BEAT-AML and MDACC). Spatial deconvolution of 3 patients using whole transcriptomic GeoMx revealed that primitive cells were more likely to be proximal to bone, while more differentiated states were enriched in distal region from the bone. Our findings reveal complex hierarchies in AML cells sharing the LSC expression pattern, while more primitive cells were likely to localize to bone regions suggesting spatial migration of AML cells at time of differentiation. Citation Format: Bofei Wang, Christopher Ly, Fatima Zahra Jelloul, Enes Dasdemir, Guilin Tang, Sonali Jindal, Yulong Chen, Sreyashi Basu, Poonam Desai, Pamella Borges, Preethi Gunaratne, Natalia Baran, Qing Deng, Dapeng Hao, Sean Post, Michael Green Green, Marina Konopleva, Andy Futreal, Padmanee Sharma, Hussein A. Abbas. Leveraging single cell RNA profiling to uncover intra-tumor heterogeneity across cytogenetic subgroups in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5927.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) with unusual features, including some that can overlap morphologically with classic Hodgkin lymphoma (CHL), have been described. Herein, we describe 12 cases of NLPHL with fibrous bands and capsular fibrosis resembling, in part, nodular sclerosis (NS) CHL. Seven of 12 cases harbored Reed-Sternberg-like cells, further suggestive of CHL, but all cases lacked associated eosinophils and/or plasma cells in the background. In this cohort, all cases had areas of so-called pattern D (nodular T-cell rich) as a sole component in 7 (58%) cases or as a hybrid pattern along with pattern E (diffuse T-cell/histiocyte-rich) in 5 (42%) cases. The immunophenotype of the large neoplastic cells in these cases supported their being lymphocyte predominant cells of NLPHL, positive for CD20, CD79a, and OCT2, and negative for CD15 and CD30. However, PAX5 was weak in 9 of 11 cases similar to Hodgkin/Reed-Sternberg cells in CHL. We conclude that some cases of NLPHL are associated with fibrous bands and capsular fibrosis and resemble, in part, NS CHL. In our experience, NLPHL with NS-like features occurs in 10% to 15% of cases of NLPHL and is associated with a variant pattern (D and/or E). In addition, all patients in this cohort were not treated before biopsy, suggesting that the prominent sclerosis in these cases is inherent to disease biology. Recognition of NLPHL with NS-like features further expands the morphologic spectrum of NLPHL and helps avoid potential misdiagnosis as CHL.

Prompt diagnosis of acute promyelocytic leukemia (APL) is critical for patient care. In this study, we aimed to characterize the immunophenotype of APL and explore immunophenotypic difference between APL and its mimics using flow cytometric analysis.Eighty-five cases were collected, including 47 APL, 26 NPM1-mutated acute myeloid leukemia (AML) and 12 KMT2A-rearranged AML with an APL-like immunophenotype. Immunophenotypes were analyzed using flow cytometric analysis.APL showed four distinct patterns (designated a-d) based on CD45/SSC plots. Blasts in patterns a-c showed high side scatter, whereas blasts in pattern d had low side scatter and were located in the traditional blast gate. Compared with patterns a-c, pattern d of APL (APL-D) was more often positive for CD2 (p = 0.0005) and CD34 (p = 0.0002) in blasts. All NPM1-mutated AML and KMT2A-rearranged AML cases with an APL-like immunophenotype had blasts in the traditional blast gate on CD45/SSC, mimicking APL-D. In comparison, uniform CD13 and positive CD64 were seen in 100% (n = 13) APL-D cases and in only 2 of 26 (8%) NPM1-mutated AML cases (p 0.0001). In addition, APL-D cases were more likely to be positive for CD2 and/or CD34 than NPM1-mutated AML (p 0.0001 and p = 0.0007, respectively). In comparison with APL-D, KMT2A-rearranged AML cases were less often positive for myeloperoxidase (MPO) (p = 0.001), with none being strongly positive. Similar to NPM1-mutated AML and different from APL-D, KMT2A-rearranged AML cases were rarely positive for CD34 and all negative for CD2.APL and its immunophenotypic mimics share some immunophenotypic similarities but can be distinguished by CD2, CD13, CD34, CD64, and MPO.

NOTCH1 is one of the most frequently mutated genes in chronic lymphocytic leukemia and has emerged as a marker of poor prognosis. In addition to coding NOTCH1 mutations involving exon 34, non-coding NOTCH1 mutations involving the 3' UTR have been described in a limited number of chronic lymphocytic leukemia (CLL) patients and were associated with adverse outcomes. In this study, 1574 CLL patients were assessed using targeted sequencing with a 29 gene panel and the results were correlated with prognostic characteristics. NOTCH1 mutations were detected in 252 (16%) patients, including both coding (220/252, 14%), non-coding (24/252, 1.5%) and a mixture of coding and non-coding (8/252, 0.5%) NOTCH1 mutations. NOTCH1 mutations were more commonly seen in patients with unmutated IGHV, ZAP70 positivity and CD38 positivity. Mixed NOTCH1 mutations were also more commonly seen in patients with unmutated IGHV and ZAP70. There was no association between mixed NOTCH1 mutations and CD38 expression in this cohort. The most common cytogenetic alteration detected in patients with coding and mixed NOTCH1 mutations was trisomy 12, whereas del13q was the most common cytogenetic alteration detected in patients with non-coding NOTCH1 mutation. The most common gene mutations co-occurring with coding NOTCH1 mutations were: TP53 (23.2%), SF3B1 (16.4%) and SPEN (10%). The most common gene mutations co-occurring with non-coding NOTCH1 mutations were: SF3B1 11(34.4%), ATM 4(12.5%) and TP53 4(12.5%). CLL patients with clonal coding and non-coding NOTCH1 mutations had a significantly shorter time-to-first treatment than patients with wild type NOTCH1 (4.3 vs 10.0 years and 0.9 vs 10.0 years respectively, p 0.05). Similarly, CLL patients with subclonal coding NOTCH1 mutations had a significantly shorter time-to-first treatment than patients with wild type NOTCH1 (5.6 vs 10.0 years, p 0.05). CLL patients with subclonal non-coding NOTCH1 mutations also had a shorter time-to-first treatment than patients with wild type NOTCH1 mutations, however, the difference was not significant (5.1 vs 10.0 years, p = 0.15). These data confirm that both coding and non-coding NOTCH1 mutations carry adverse prognostic impact and need to be included in sequencing assays performed for the prognostic workup of CLL patients.

The development of clonally related hematologic neoplasms in the setting of primary mediastinal germ cell tumors (PMGCTs) has been recognized previously and is associated with a dismal prognosis. However, the presentation of hematologic neoplasms as chronic myelomonocytic leukemia (CMML) and hemophagocytic lymphohistiocytosis (HLH) has been rarely reported. Here we report two patients with PMGCTs and hematologic neoplasms. The PMGCT was composed mostly of yolk sac tumor whereas the hematologic neoplasms had morphologic features that resembled CMML and HLH. The hematologic neoplasms from both patients harbored isochromosome 12p [i(12p)] and TP53 mutations, supporting a clonal relationship between these tumors. This association represents a unique clinical syndrome that likely contributes to the poor clinical outcome of these patients.

Patients with advanced solid malignancies recurrent or resistant to standard therapy have limited treatment options. The role of molecular biomarkers for predicting immune checkpoint blockade (ICB) efficacy are not well characterized in these patients. Tumor mutational profiles of 490 patients with a variety of advanced solid tumors enrolled in a prospective protocol were analyzed to identify prognostic and predictive biomarkers. ICB therapy was defined as treatment with any CTLA-4, PD-1, and/or PD-L1 monoclonal antibody. ICB treatment was associated with significantly improved overall survival compared to non-ICB therapy. Multivariate regression analysis including the two variables of tumor mutation burden (TMB) and ICB, and their interaction term, showed favorable survival associated with ICB, unfavorable survival associated with TMB without ICB treatment, and improved outcome with increasing TMB in ICB treated patients. Tumor TP53 mutation was associated with worse survival, but these patients still benefitted from ICB. A more comprehensive multivariate analysis including cancer type, specific gene mutations, and TMB revealed that ICB treatment was an independent predictor of improved overall survival. Therefore, ICB-based therapeutic trials are beneficial in patients with advanced solid malignancies, but the most benefit may be restricted to patients with the right combination of TMB and specific tumor histology and genotype.

Well-differentiated systemic mastocytosis (WDSM) is a rare unique variant of systemic mastocytosis that has been described in few studies [1–11]. This entity has unique features that can cause pote...

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous and often clinically aggressive group of neoplasms derived from mature post-thymic T-lymphocytes. These neoplasms are rare and usually diagnostically challenging. Our understanding of the pathogenesis of PTCL is increasing and this improved knowledge is leading us to better molecular characterization, more objective and accurate diagnostic criteria, more effective risk assessment, and potentially better treatments. The focus of this paper is to present a brief overview of the current pathology criteria and molecular and genetic features of nodal peripheral T-cell lymphomas focusing on distinct genetically and molecularly defined subgroups that are being recognized within each major nodal PTCL category. It is expected that the molecular stratification will improve the diagnosis and will provide novel therapeutic opportunities (biomarker-driven and targeted therapies) that might benefit and change the outcomes of patients with these neoplasms.

Previously considered rare, inherited hematologic malignancies are increasingly identified. Germline mutations in the RNA helicase DDX41 predispose to increased lifetime risks of myeloid neoplasms with disease often occurring later in life which presents challenges for germline recognition. To improve identification of germline DDX41, individuals presenting with ≥1 DDX41 alteration on an institutional MDS/AML next-generation sequencing based panel with at least one at >40% variant allele frequency were flagged for review and genetic counseling referral. Of 5,801 individuals, 90 (1.5%) had ≥1 DDX41 mutation(s) identified. Thirty-eight (42%) patients with a median age of 66 years were referred for genetic counseling; thirty-one were male (81.5%). Thirty-five (92%) referred patients elected to pursue germline evaluation and in 33/35 (94%) a germline DDX41 variant was confirmed. Twenty-two patients (66%) with germline variants reported antecedent cytopenias, seven (21%) had a prior history of malignancy, and twenty-seven (82%) reported a family history of cancer. Predictive genetic testing for healthy family members under consideration as stem cell transplant donors was successfully performed in 11 family members, taking an average of 15 days. Near-heterozygous DDX41 mutations identified on next-generation sequencing, particularly nonsense/frameshift variants or those at recurrent germline “hot spots” are highly suggestive of a germline mutation. Next-generation sequencing screening is a feasible tool to screen unselected myeloid neoplasms for germline DDX41 mutations, enabling timely and appropriate care.

BACKGROUND The Bethesda system (TBS) for the reporting of thyroid cytopathology established the category of atypia of undetermined significance (AUS) with a 7% target rate and a 5% to 15% implied malignancy risk. Recent literature has reported a broad range of AUS rates, subsequent malignancy rates, and discrepant results from repeat fine-needle aspiration (FNA) versus surgical follow-up. Therefore, this study examined AUS data from the Hofstra North Shore–LIJ School of Medicine to determine the best clinical follow-up. METHODS Thyroid aspirates interpreted as AUS in 2012-2014 at the Hofstra North Shore–LIJ School of Medicine were collected. Repeat FNA and surgical follow-up data were tabulated to establish AUS, secondary AUS (diagnosed upon repeat FNA follow-up of a primary FNA AUS diagnosis), atypia of undetermined significance/malignancy (AUS:M) ratios (according to the TBS categories), and malignancy rates for AUS. RESULTS The AUS rate was 8.5% (976/11,481), and there was follow-up data for 545 cases. The AUS:M ratio was 2.0. Repeat FNA was performed for 281 cases; 57 proceeded to surgical intervention. Repeat FNA reclassified 71.17% of the cases. The malignancy rates for AUS cases proceeding directly to surgery and for those receiving a surgical intervention after a repeat AUS diagnosis were 33.33% and 43.75%, respectively. CONCLUSIONS Repeat FNA resulted in definitive diagnostic reclassification for 67.61% of primary AUS cases and reduced the number of patients triaged to surgery, with 56.58% of the cases recategorized as benign. Cases undergoing surgery after repeat AUS had a higher malignancy rate than those going straight to surgery, and this emphasizes the value of repeat FNA in selecting surgical candidates. In addition, this study highlights the utility of AUS rate monitoring as a quality measure that has contributed to the ability of the Hofstra North Shore–LIJ School of Medicine to adhere closely to TBS recommendations. Cancer (Cancer Cytopathol) 2016;124:37-43. © 2016 American Cancer Society.

BACKGROUND Cadherin-17 (intestinal peptide-associated transporter) and SATB2 (SATB homeobox 2) immunoexpression has recently been described in surgical pathology to have value in establishing the colorectal origin of metastatic adenocarcinoma. However, to the authors' knowledge, the role of these markers in metastatic colorectal adenocarcinoma (MCA) in cytology has not been addressed to date. In the current study, the authors evaluated the contribution of cadherin-17 and SATB2 to the diagnosis of MCA in cytology specimens and compared these two novel markers with the standard gastrointestinal immunohistochemistry panel in an attempt to identify the optimal panel. METHODS A total of 43 MCA cytology cases and 68 metastatic noncolorectal adenocarcinoma (non-MCA) cytology controls were stained for SATB2; cadherin-17; and the standard panel of cytokeratin (CK) 7, CK20, and Caudal-Type Homeobox Transcription Factor 2 (CDX2). Staining intensity and percentage of positive cells were recorded. Sensitivity and specificity values for immunostains individually and in combination were computed and compared. RESULTS Despite specificities of 83.8% and 91.2%, respectively, for cadherin-17 and SATB2, when critically examining the new immunostains together with the standard panel, there was no significant difference noted with regard to prediction of MCA (vs non-MCA) compared with the standard panel alone (P

Background: Composite small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) and follicular lymphoma (FL) is extremely rare, and only 13 cases have been reported previously. Methods: We identified 6 cases of composite SLL/CLL and FL in our database and studied their clinical, histologic, immunophenotypic, and cytogenetic features. A literature review of the existing cases was also conducted. Results: The patients included 4 males and 2 females, with a median age of 72 years. Four patients presented with lymphadenopathy and 2 with extranodal diseases. Lymphocytosis was seen in 2 cases. Serum lactate dehydrogenase levels were within normal range in all but one case. There were 2 histologic patterns: SLL/CLL predominant pattern (type I) and FL predominant or mixed pattern (type II). The type I pattern was exclusively associated with in situ follicular neoplasia (ISFN). The SLL/CLL showed typical morphology and immunophenotype in all the cases. The FL component included low grade (n = 3), ISFN (n = 2), and primary cutaneous FL (n = 1). Four cases had staging bone marrow biopsies including 3 cases with involvement by SLL/CLL and 1 case with involvement by SLL/CLL and FL. Four patients received treatments, one was under clinical surveillance, and one had no available information. All patients were alive after a median follow-up of 22 months. Conclusions: This is the largest case serial of composite SLL/CLL and FL. The CL affects elderly individuals, presents with advanced clinical stage, and appears to have a relatively indolent clinical course.

Esophageal schwannoma is a rare tumor first described in 1967 by Chaterlin and Fissore. These tumors are most commonly found incidentally or from diagnostic work up of dysphagia or dyspnea. This entity cannot be diagnosed on clinical or radiographic basis alone. Histology demonstrates palisading spindle cells, few if any mitotic figures, and a peripheral cuff of lymphoid cells. Immunohistochemically, tumor cells stain positive for S100, a characteristic marker of Schwann cells. Once diagnosed, surgical enucleation is the typical treatment method employed.

Introduction: Kaposi sarcoma-associated herpesvirus (KSHV)- and Epstein-Barr virus-associated germinotropic lymphoproliferative disorder (GLD) is a rare disorder of immunocompetent adults presenting with localized lymphadenopathy. GLD differs from other KSHV-associated diseases in their indolent clinical behavior, good therapeutic response, and polyclonal gene rearrangement. As few cases have been reported, more cases are necessary to better educate pathologists. Here we describe a case …