The prevalence of extramedullary acute myeloid leukemia detected by 18FDG-PET/CT: final results from the prospective PETAML trial

Extramedullary infiltration in pediatric acute myeloid leukemia: Results from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) initiative

BACKGROUND

The outcome of extramedullary infiltration (EMI) in pediatric acute myeloid leukemia (AML) is controversial, and little is known about the implications of stem cell transplantation (SCT) and gemtuzumab ozogamicin (GO) treatment on patients with EMI.

METHODS

We retrieved the clinical data of 713 pediatric patients with AML from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) dataset, and analyzed the clinical and prognostic characteristics of patients with EMI at diagnosis and relapse.

RESULTS

A total of 123 patients were identified to have EMI at diagnosis and 64 presented with EMI at relapse. The presence of EMI was associated with age ≤2 years, M5 morphology, abnormal karyotype, and KMT2A rearrangements. Hyperleukocytosis and complex karyotype were more prevalent in patients with EMI at relapse. Additionally, patients with EMI at diagnosis had a reduced incidence of FLT3 ITD-/NPM1+, whereas those with EMI at relapse displayed a lower frequency of FLT3 ITD+. Patients with EMI at diagnosis exhibited a lower complete remission (CR) rate at the end of Induction Course 1 and higher relapse incidence. Importantly, EMI at diagnosis independently predicted both shorter event-free survival (EFS) and overall survival (OS). Regarding relapse patients, the occurrence of EMI at relapse showed no impact on OS. However, relapse patients with myeloid sarcoma (MS)/no central nervous system (CNS) exhibited poorer OS compared to those with CNS/no MS. Furthermore, regarding patients with EMI at diagnosis, SCT failed to improve the survival, whereas GO treatment potentially enhanced OS.

CONCLUSION

EMI at diagnosis is an independent adverse prognostic risk factor for pediatric AML, and GO treatment potentially improves survival for patients with EMI at diagnosis.

PET/CT in leukemia: utility and future directions

2-Deoxy-2-[18F]fluoro-d-glucose PET/computed tomography ([18F]FDG PET/CT) has proven to be a sensitive method for the detection and evaluation of hematologic malignancies, especially lymphoma. The increasing incidence and mortality rates of leukemia have raised significant concerns. Through the utilization of whole-body imaging, [18F]FDG PET/CT provides a thorough assessment of the entire bone marrow, complementing the limited insights provided by biopsy samples. In this regard, [18F]FDG PET/CT has the ability to assess diverse types of leukemia The utilization of [18F]FDG PET/CT has been found to be effective in evaluating leukemia spread beyond the bone marrow, tracking disease relapse, identifying Richter's transformation, and assessing the inflammatory activity associated with acute graft versus host disease. However, its role in various clinical scenarios in leukemia remains unacknowledged. Despite their less common use, some novel PET/CT radiotracers are being researched for potential use in specific scenarios in leukemia patients. Therefore, the objectives of this review are to provide a thorough assessment of the current applications of [18F]FDG PET/CT in the staging and monitoring of leukemia patients, as well as the potential for an expanding role of PET/CT in leukemia patients.

Pretransplant hepatomegaly is linked to relapse in patients with leukemia and myelodysplastic syndrome not in remission

Hepatomegaly is an extramedullary disease (EMD) manifestation of hematological malignancy. Although EMD before allogeneic hematopoietic stem cell transplantation (allo-HCT) is a risk factor for relapse in patients not in complete remission (NonCR) patients, the significance of hepatomegaly to allo-HCT is unclear. We conducted a single-center retrospective observational study of 140 patients with acute leukemia and myelodysplastic syndrome who underwent allo-HCT at our institution from 2014 to 2019. Hepatomegaly was assessed by ultrasonography using the liver index (LI). In the univariable analysis, the LI/height ratio was significantly associated with relapse (hazard ratio [HR] per standard deviation [sd]: 1.51, 95% confidence interval [CI] 1.18-1.93, p = 0.001, sd = 13.8) in NonCR patients (n = 62), but showed no significant association in CR patients (n = 78) (HR per sd: 0.95, 95% CI 0.64-1.39, p = 0.780, sd = 8.7). In multivariable analysis, the LI/height ratio was significantly associated with relapse (HR per sd: 1.34, 95% CI 1.02-1.78, p = 0.037) after adjusting for the refined disease risk index and conditioning intensity. Interaction analysis showed a noteworthy but not statistically significant association between the LI/height ratio and CR status (p = 0.110). In conclusion, our findings suggest that the LI may be a risk factor for relapse in NonCR patients after allo-HCT.

Acute Leukemia Relapse after Hematopoietic Stem Cell Transplantation: The Good, the Bad, and the Ugly of Isolated Extramedullary Relapse in a Latin American Population

Hematopoietic stem cell transplantation (HSCT) is an effective therapy for acute leukemia (AL). Relapse represents the main cause of mortality. Isolated extramedullary relapse (iEMR) is atypical and has been related to better outcomes. Here we describe the clinical characteristics and outcomes of AL relapse after HSCT in our study population and analyze the impacts of different types of relapse on survival outcomes. This retrospective, multicenter study included 124 patients age ≥15 years with AL who underwent HSCT between 2004 and 2019. At diagnosis, 66.1% of the patients had lymphocytic AL, 19.7% presented with high-risk features, and 18.5% had extramedullary disease (EMD). At HSCT, 83.1% of the patients were in complete remission (CR), and 44.8% had negative measurable residual disease (MRD). The vast majority of donors were related (96%), including 48.4% HLA-matched and 47.6% haploidentical. Myeloablative conditioning was provided to 80.6% of patients. The median overall survival (OS) was 15 months (95% confidence interval [CI] 9.9 to 20.1 months). Factors associated with improved OS were adolescent and young adult (AYA) patient (P = .035), first or second CR (P = .026), and chronic graft-versus-host disease (GVHD) (P < .001). Acute GVHD grade III-IV (P = .009) was associated with increased mortality. The median relapse-free survival was 13 months (95% CI, 7.17 to 18.8 months); early disease status (P = .017) and chronic GVHD (P < .001) had protective roles. Sixty-eight patients (55%) relapsed after HSCT, with a median time to relapse of 6 months (95% CI, 3.6 to 8.4 months). iEMR was reported in 16 patients (23.5%). The most commonly involved extramedullary sites were the central nervous system and skin. Compared to patients with bone marrow relapse, all patients with iEMR had a diagnosis of acute lymphoid leukemia (P = .008), and 93.8% belonged to the AYA group; regarding pre-HSCT characteristics, iEMR patients had higher rates of negative MRD (P = .06) and a history of EMD (P = .009). Seventy-seven percent of relapsed patients received additional treatment with curative intent. The median OS after relapse (OSr) was 4 months (95% CI, 2.6 to 5.4 months). Factors related to increased OSr included lymphoid phenotype (P = .03), iEMR (P = .0042), late relapse (≥6 months) (P = .014), receipt of systemic therapy including second HSCT (P < .001), and response to therapy (P < .001). Rates of relapse and iEMR were higher than those previously reported in other studies. Advanced disease, reduced-intensity conditioning, and a diminished graft-versus-leukemia effect were factors influencing these findings. At relapse, presenting with iEMR after 6 months and receiving intensive therapy with adequate response were associated with better outcomes. Our results strongly suggest that a personalized approach to treating patients with HSCT is needed to counterbalance specific adverse factors and can positively impact clinical outcomes.

Orbital Involvement in Acute Adult Leukemias: Case Series and Review of Literature

Orbital involvement in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) is well-described in children but is uncommon in adults. This series reports 2 adult patients with orbital leukemic involvement and summarizes the existing literature. A 37-year-old male with recently diagnosed AML underwent induction therapy and subsequently developed a tan-pink colored sub-conjunctival lesion in the left eye. Incisional biopsy confirmed AML. A 35-year-old male with history of ALL presented with left-sided orbital mass. Fine needle aspiration biopsy confirmed ALL. Literature review of adult-onset orbital leukemia yielded 29 cases of AML and 3 cases of ALL. Orbital involvement of acute adult-onset leukemia tends to be unilateral, presents in the extraconal space and can occur at any point during systemic leukemic disease. Chemotherapy is the mainstay of treatment, often in combination with radiation and/or hematopoietic stem cell transplant.

Glucose partitioning in the bone marrow micro-environment in acute myeloid leukaemia

Acute myeloid leukaemia (AML) cells metabolise glucose by glycolysis-based re-programming. However, how glucose uptake is partitioned between leukaemia cells and other cells of the bone marrow micro-environment is unstudied. We used a positron emission tomography (PET) tracer ¹⁸F fluorodeoxyglucose ([¹⁸F]-FDG) probe and transcriptomic analyses to detect glucose uptake by diverse cells in the bone marrow micro-environment in a MLL-AF9-induced mouse model. Leukaemia cells had the greatest glucose uptake with leukaemia stem and progenitor cells having the greatest glucose uptake. We also show the effects of anti-leukaemia drugs on leukaemia cell numbers and glucose uptake. Our data suggest targeting glucose uptake as a potential therapy strategy in AML if our observations are validated in humans with AML.

Myeloid sarcoma: An overview

Myeloid Sarcoma (MS) is a high grade, hematological malignancy defined as an extramedullary tumor mass of myeloid blasts with or without maturation that effaces tissue architecture. It is a highly heterogenous condition that represents a variety of myeloid neoplasms. This heterogeneity of MS, together with its rarity, have greatly hampered our understanding of the condition. Diagnosis requires tumor biopsy, which should be accompanied by bone marrow evaluation for medullary disease. It is presently recommended that MS be treated similar to AML. Additionally, ablative radiotherapy and novel targeted therapies may also be beneficial. Genetic profiling has identified recurrent genetic abnormalities including gene mutations associated with MS, supporting its etiology similar to AML. However, the mechanisms by which MS homes to specific organs is unclear. This review provides an overview of pathogenesis, pathological and genetic findings, treatment, and prognosis. Improving the management and outcomes of MS patients requires a better understanding of its pathogenesis and its response to various therapeutic approaches.

RNA sequencing of myeloid sarcoma, shed light on myeloid sarcoma stratification

BACKGROUND

Myeloid sarcoma (MS) is a rare, extramedullary tumor consisting of myeloid blasts. Little is known about the genetic background of MS and the prognostic value of genetic abnormalities in MS. In particular, the broad variety of gene fusions that occur in MS is marginally covered by traditional testing methods due to lack of fresh tumor specimens.

METHODS

Here, we analyzed the clinical and genetic features of 61 MS cases. We performed RNA sequencing (RNA-seq) on formalin-fixed paraffin-embedded (FFPE) or fresh samples to analyze fusion genes in 26 cases. In addition, we performed genetic abnormalities-based risk stratification using fusion genes and gene mutations.

RESULTS

A total of 305 fusion genes were identified in 22 cases, including the following five recurrent fusion genes: RUNX1-RUNX1T1, CBFβ-MYH11, ETV6-MECOM, FUS-ERG, and PICALM-MLLT10. The prognosis in the adverse-risk group was significantly worse than that in the favorable/intermediate-risk group (median survival: 12 months vs. not reached; p = 0.0004).

CONCLUSION

These results indicated the efficacy of RNA-seq using FFPE-derived RNA as a clinical routine for detecting fusion genes, which can be used as markers for risk stratification in MS.

Gene Mutations and Targeted Therapies of Myeloid Sarcoma

OPINION STATEMENT

Myeloid sarcoma, a rare malignant tumor characterized by the invasion of extramedullary tissue by immature myeloid cells, commonly occurs concomitantly with acute myeloid leukemia, myelodysplastic syndromes, or myeloproliferative neoplasms. The rarity of myeloid sarcoma poses challenges for diagnosis and treatment. Currently, treatments for myeloid sarcoma remain controversial and primarily follow protocols for acute myeloid leukemia, such as chemotherapy utilizing multi-agent regimens, in addition to radiation therapy and/or surgery. The advancements in next-generation sequencing technology have led to significant progress in the field of molecular genetics, resulting in the identification of both diagnostic and therapeutic targets. The application of targeted therapeutics, such as FMS-like tyrosine kinase 3(FLT3) inhibitors, isocitrate dehydrogenases(IDH) inhibitors, and the B cell lymphoma 2(BCL2) inhibitors, has facilitated the gradual transformation of traditional chemotherapy into targeted precision therapy for acute myeloid leukemia. However, the field of targeted therapy for myeloid sarcoma is relatively under-investigated and not well-described. In this review, we comprehensively summarize the molecular genetic characteristics of myeloid sarcoma and the current application of targeted therapeutics.

Myeloid Sarcoma: A Primer for Radiologists

ABSTRACT

Myeloid sarcoma (MS) is a rare extramedullary neoplasm that can present in association with acute myeloid leukemia, most commonly in children younger than 15 years. This unique extramedullary malignancy may involve a variety of different organ systems and can present following, preceding, simultaneous with, or in insolation to acute myeloid leukemia. Common areas of extramedullary involvement include soft tissues, bones, lymph nodes, and the peritoneum. Imaging plays a critical role in the diagnosis and management of MS, with commonly used modalities including positron emission tomography-computed tomography, magnetic resonance imaging, computerized tomography, and ultrasound. The purpose of this review article is to provide radiologists with a comprehensive guide summarizing the relevant imaging and clinical features of MS, with emphasis on the role of imaging in the diagnosis, treatment, and follow-up of patients with MS. The relevant pathophysiology, epidemiology, clinical presentations, and differential diagnosis of MS will be reviewed. The relevance of different imaging modalities in diagnosis, monitoring of treatment response, and assessment of treatment-related complications will also be outlined. Through summarizing these topics, this review article aims to provide radiologists with a guide for understanding the existing knowledge of MS in the literature and the current role of imaging in the management of this unique malignancy.

Pediatric Myeloid Sarcoma, More than Just a Chloroma: A Review of Clinical Presentations, Significance, and Biology

Myeloid sarcomas (MS), commonly referred to as chloromas, are extramedullary tumors of acute myeloid leukemia (AML) with varying incidence and influence on outcomes. Pediatric MS has both a higher incidence and unique clinical presentation, cytogenetic profile, and set of risk factors compared to adult patients. Optimal treatment remains undefined, yet allogeneic hematopoietic stem cell transplantation (allo-HSCT) and epigenetic reprogramming in children are potential therapies. Importantly, the biology of MS development is poorly understood; however, cell-cell interactions, epigenetic dysregulation, cytokine signaling, and angiogenesis all appear to play key roles. This review describes pediatric-specific MS literature and the current state of knowledge about the biological determinants that drive MS development. While the significance of MS remains controversial, the pediatric experience provides an opportunity to investigate mechanisms of disease development to improve patient outcomes. This brings the hope of better understanding MS as a distinct disease entity deserving directed therapeutic approaches.

C1Q labels a highly aggressive macrophage-like leukemia population indicating extramedullary infiltration and relapse

Extramedullary infiltration (EMI) is a concomitant manifestation that may indicate poor outcome of acute myeloid leukemia (AML). The underlying mechanism remains poorly understood and therapeutic options are limited. Here, we employed single-cell RNA sequencing on bone marrow (BM) and EMI samples from a patient with AML presenting pervasive leukemia cutis. A complement C1Q+ macrophage-like leukemia subset, which was enriched within cutis and existed in BM before EMI manifestations, was identified and further verified in multiple patients with AML. Genomic and transcriptional profiling disclosed mutation and gene expression signatures of patients with EMI that expressed high levels of C1Q. RNA sequencing and quantitative proteomic analysis revealed expression dynamics of C1Q from primary to relapse. Univariate and multivariate analysis demonstrated adverse prognosis significance of C1Q expression. Mechanistically, C1Q expression, which was modulated by transcription factor MAF BZIP transcription factor B, endowed leukemia cells with tissue infiltration ability, which could establish prominent cutaneous or gastrointestinal EMI nodules in patient-derived xenograft and cell line-derived xenograft models. Fibroblasts attracted migration of the C1Q+ leukemia cells through C1Q-globular C1Q receptor recognition and subsequent stimulation of transforming growth factor β1. This cell-to-cell communication also contributed to survival of C1Q+ leukemia cells under chemotherapy stress. Thus, C1Q served as a marker for AML with adverse prognosis, orchestrating cancer infiltration pathways through communicating with fibroblasts and represents a compelling therapeutic target for EMI.

Spatial heterogeneity and differential treatment response of acute myeloid leukemia and relapsed/refractory extramedullary disease after allogeneic hematopoietic cell transplantation

Although extramedullary manifestations (EMs) are frequent in patients with acute myeloid leukemia (AML), they are often not detected during clinical workup and neither imaging- nor molecularly based diagnostic strategies are established to reveal their existence. Still, the detection of EM is essential for therapeutic decision-making, as EM present with aggressive and resistant disease and since mutational profiling might render patients within a different risk category, requiring personalized therapeutic strategies. Here, we report the case of an AML patient presenting with AML bone marrow (BM) infiltration and molecularly distinct EM at time of diagnosis followed by multiple EM relapses while undergoing several intensive chemotherapies including allogeneic hematopoietic cell transplantations (alloHCTs). ¹⁸Fluorodesoxy-glucose positron emission tomography (¹⁸FDG-PET)-imaging revealed EM sites in the mediastinum, duodenum, skin, and in retroperitoneal tissue, whereas recurrent BM biopsies showed continuous cytomorphologic and cytogenetic remission after alloHCT. To investigate the molecular background of the aggressive character of extramedullary disease and its differential treatment response, we performed amplicon-based next generation sequencing. An exon 4 (c.497_498insGA) frameshift RUNX1 mutation was exclusively found in all of the patient’s EM sites, but not in the BM or in peripheral blood samples at time of EM reoccurrence. In addition, we detected an exon 13 (c.3306G>T) ASXL1 point mutation only in the retroperitoneal tumor tissue at the time of the fourth relapse. In contrast to the patient’s intermediate-risk BM AML at diagnosis according to ELN2017, EM sites showed molecular adverse-risk features implicating intensified strategies like cellular therapies. Notably, disease relapse could only be detected by imaging throughout the course of disease. This case demonstrates both the necessity of continuous molecular profiling of EM to reveal differential molecular composition of EM and BM-derived AML, supposedly leading to divergent susceptibility to established therapies, as well as recurrent ¹⁸FDG-PET-imaging for detecting residual disease and assessment of treatment response in case of EM AML.

Molecular profiling and clinical implications of patients with acute myeloid leukemia and extramedullary manifestations

Background

Extramedullary manifestations (EM) are rare in acute myeloid leukemia (AML) and their impact on clinical outcomes is controversially discussed.

Methods

We retrospectively analyzed a large multi-center cohort of 1583 newly diagnosed AML patients, of whom 225 (14.21%) had EM.

Results

AML patients with EM presented with significantly higher counts of white blood cells (p < 0.0001), peripheral blood blasts (p < 0.0001), bone marrow blasts (p = 0.019), and LDH (p < 0.0001). Regarding molecular genetics, EM AML was associated with mutations of NPM1 (OR: 1.66, p < 0.001), FLT3-ITD (OR: 1.72, p < 0.001) and PTPN11 (OR: 2.46, p < 0.001). With regard to clinical outcomes, EM AML patients were less likely to achieve complete remissions (OR: 0.62, p = 0.004), and had a higher early death rate (OR: 2.23, p = 0.003). Multivariable analysis revealed EM as an independent risk factor for reduced overall survival (hazard ratio [HR]: 1.43, p < 0.001), however, for patients who received allogeneic hematopoietic cell transplantation (HCT) survival did not differ. For patients bearing EM AML, multivariable analysis unveiled mutated TP53 and IKZF1 as independent risk factors for reduced event-free (HR: 4.45, p < 0.001, and HR: 2.05, p = 0.044, respectively) and overall survival (HR: 2.48, p = 0.026, and HR: 2.63, p = 0.008, respectively).

Conclusion

Our analysis represents one of the largest cohorts of EM AML and establishes key molecular markers linked to EM, providing new evidence that EM is associated with adverse risk in AML and may warrant allogeneic HCT in eligible patients with EM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01267-7.

Clinical characteristics, pathology features and outcomes of pediatric myeloid sarcoma: A retrospective case series

PURPOSE

Myeloid sarcoma (MS) is a rare extramedullary mass with myeloid expression, which is easy to be missed and misdiagnosed, especially in the pediatric population. We analyze the clinicopathological characteristics, immunophenotypic, cytogenetic, and molecular studies, therapeutic approaches, and outcomes, to optimize the management of such patients.

METHODS

A retrospective, single-center, case series study of eleven children diagnosed with MS by pathology was performed.

RESULTS

The male-to-female ratio was 8:3, and the median age at diagnosis was 7 years. The most commonly involved sites were the skin and orbital region, followed by lymph nodes, central nervous system, and testis. Seven cases (64%) with Class I-MS and four cases (36%) presented as Class II-MS. Immunohistochemically, MPO and CD117 were the most commonly expressed markers, followed by CD33, CD43, CD34, CD68, and lysozyme. Chromosomal abnormalities were detected in 4 patients. Two patients had the presence of deleterious mutations (FLT3, ASXL, KIT, and DHX15) on molecular detection. Ten patients were treated with chemotherapy based on AML regimens. The median follow-up time was 33.5 months in eleven patients. Two patients relapsed, one died, and one lost to follow-up. The 2-year overall survival (OS) rate estimated by Kaplan-Meier curves was 90.9% ± 8.7%, and the event-free survival (EFS) rate was 64.9% ± 16.7%.

CONCLUSIONS

MS diagnosis is usually challenging. Adequate tumor biopsy and expanded immunohistochemistry are necessary for the correct diagnosis of MS. Early and regular systemic chemotherapy promises long-term survival.

Analysis of PET parameters predicting response to radiotherapy for myeloid sarcoma

Purpose

Positron-emission tomography (PET)-CT has recently been used for diagnostic imaging and radiotherapy for myeloid sarcoma, but there is little research on predicting the response of radiotherapy. The aim of this study was to analyze the association between PET-CT variables and the response to radiotherapy in patients with myeloid sarcoma.

Materials and methods

This study was conducted in myeloid sarcoma patients who received radiotherapy and PET-CT before and after radiotherapy. The response to radiotherapy was evaluated based on the European Organization for Research and Treatment of Cancer PET response criteria, and binary regression analysis was performed to assess the factors predicting reductions in the maximum standardized uptake value (SUVmax).

Results

Twenty-seven sites in 12 patients were included in the study. Complete metabolic responses were seen in 24 patients after radiotherapy, a partial metabolic response in one, and progressive metabolic disease in two patients. The prescribed dose of more than 3000 cGy₁₀ was significantly greater in the treatment control group (P = 0.024). In binary logistic regression analysis predicting reductions in the SUVmax of more than 70% after radiotherapy, the pretreatment SUVmax (≥ 7.5) and further chemotherapy after radiotherapy showed significant differences in univariate and multivariate analyses.

Conclusion

Good metabolic responses (complete or partial) to radiotherapy were achieved in 92.6% of the myeloid sarcoma patients. Radiation doses < 3000 cGy₁₀ and increased SUVmax were related to treatment failure and high SUVmax before radiotherapy was a factor influencing SUVmax reduction. Further large-scale studies are needed.

Extramedullary acute myeloid leukemia (eAML): Retrospective single center cohort study on clinico-pathological, molecular analysis and survival outcomes

Introduction

extramedullary acute myeloid leukemia (eAML) is characterized by extramedullary tumor formation infiltrated by myeloid blasts, with or without maturation and effaced architecture. The clinical, genetic and molecular aspects and overall outcomes are well defined worldwide, but not well characterized in our region.

Purpose and methods

This is a retrospective single center cohort study on 32 patients, who were identified over 10 years to study the clinical, pathologic and genetic-molecular aspects, and survival outcomes.

Results

eAML is rare (1%), occurs at a younger age with male predominance. Central nervous system (CNS) with facial bone invasion is most commonly identified (34.4%). 45.5% were positive for conventional myeloid markers (MPO), CD33, CD117, and 36% positive for CD34 and CD68. 54% with normal karyotype had deleterious mutations on further testing. NGS revealed pathogenic mutations in 76%(N-9/17) and none tested positive for P53, IDH1 or IDH2. At a median follow up time of 43mo (range, 8.6–80mo); 37.5%(N-12) were in complete remission, 62.5%(N-20) relapsed. 28% of relapses were after allotransplant. 31%(N-10) alive and continued in complete remission(CR), and 69%(N-22) of patients have died.

Median overall survival (OS) is 18.4 and relapse free survival (RFS) 18.7 months. OS and RFS were significantly better in patients, who attained CR after induction (IC 11.9 mo vs zero; P = 0.0001; IC 12mo vs zero; P = 0.0001) compared to patients with relapsed disease; and in patients who received allo-transplant consolidation with median OS and RFS 42 vs 8.5mo (P = 0.002) and 42months vs 10 mo (P = 0.006). Thus allotransplant may be considered for all eligible patients in first CR.

Conclusion

achievement of complete remission after induction therapy is associated with improved outcomes in eAML. Allotransplant in first complete remission may be the most effective modality for achieving long-term remissions.

•

eAML is a rare entity and occurs at a younger in Jordan.

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It requires advanced methods for the diagnosis, and identification of targetable mutations, that may dictate therapeutic approaches.

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AML-like induction chemotherapy regimens remain the standard of care, and consolidation therapy is controversial.

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Failure to achieve complete remission is associated with worse survival outcomes.

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Allogeneic hematopoietic transplant may be considered in first complete remission.

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Post-transplant relapses are common and responsible for increased mortality and shorter survival.

Gastrointestinal Myeloid Sarcoma a Case Presentation and Review of the Literature

Myeloid sarcomas can be detected in up to 30% of acute myeloid leukemia cases or occur de-novo without bone marrow involvement. The most frequent localization of myeloid sarcomas in the abdominal cavity is the small intestine, and gastric presentations are infrequent, frequently misdiagnosed, and a high level of suspicion should exist when the characteristic histomorphology features are present. The current review features a case report with gastric presentation of myeloid sarcoma in a patient with a diagnosis of acute myeloid leukemia with trisomy 8. In addition, a review of the literature of intestinal-type myeloid sarcomas shows that less than 15% of these cases have been reported in the stomach. The most common molecular aberrancy detected in intestinal myeloid sarcomas is the fusion protein CBFB-MYH11. A review of several large studies demonstrates that the presence of myeloid sarcoma does not constitute an independent prognostic factor. The therapeutic approach will be tailored to the specific genetic abnormalities present, and systemic chemotherapy with hematopoietic stem cell transplant is the most efficient strategy.

Single organ microenvironment and the common features of tumors of leukemia, lymphoma, and myeloma cells growing there: A literature review

OBJECTIVE

To explore whether the growth and treatment resistance of lymphoma and myeloma tumors is similar to that previously observed in leukemic and solid tumors growing in the same organ microenvironment.

METHODS

All published cases of 3 primary hematologic malignancies in breast, without systemic involvement, were identified, with follow-ups solicited from authors. Treatment approaches were analyzed to highlight the most effective.

RESULTS

Similar histologic features and biology among primary tumors of leukemia, lymphoma, plasmacytoma, and solid breast cancer was revealed. Review of treatments: tumor-directed, chemotherapy, or combination showed the benefit of tumor removal, and use of systemic agents in adjunct, not primary, treatment. Optimal assessment is limited by few cases of PET/CT verifying limited tumor extent. The common biology observed and cases of long survival after tumor/stroma eradication point to the complicity of organ microenvironment in the chemoresistance and treatment failure commonly observed in patients.

CONCLUSIONS

The interaction of an organ microenvironment, particularly its adipocytes, with malignant cells, results in similar histologic changes, metastatic potential, and chemoresistance in 3 hematologic malignancies and solid cancers. Improved survival in hematologic malignancies could result from adopting PET/CT to find tumor and its extent, eradicating tumor, and elucidating common therapeutic targets.

PET Imaging for Hematologic Malignancies

Hematologic malignancies are a broad category of cancers arising from the lymphoid and myeloid cell lines. The 2016 World Health Organization classification system incorporated molecular markers as part of the diagnostic criteria and includes more than 100 subtypes. This article focuses on the subtypes for which imaging with positron emission tomography/computed tomography (PET/CT) has become an integral component of the patient's evaluation, that is, lymphoma and multiple myeloma. Leukemia and histiocytic and dendritic cell neoplasms are also discussed as these indications for PET/CT are less common, but increasingly seen in clinic.

Clinical and molecular characterization of myeloid sarcoma without medullary leukemia

Myeloid sarcoma (MS) in the setting of concomitant medullary AML is relatively well described, while much less is known about patients presenting with MS with <20% bone marrow blasts. We conducted a retrospective analysis of 56 patients with MS with <20% marrow blasts seen at MD Anderson between 2005 and 2020. The prevalence of MS without medullary AML was 1.4% among all newly diagnosed AML patients. The majority (75%) of patients had a single known anatomic site involved, with the skin (34%) being the most frequent. The most common histologic subtype was monocytic, and 11% of patients had a known history of an antecedent hematologic disorder. The majority of patients (70%) received frontline intensive chemotherapy induction, with 75% of those evaluable attaining complete or partial responses. The median overall survival (OS) and event-free survival (EFS) were 3.41 and 3.07 years, respectively. Patients with bone marrow blasts of ≥5% or medullary relapse had inferior outcomes, while age (>60 years) was not associated with outcomes. There was a suggestion that patients with isolated leukemia cutis may have had better outcomes compared to patients with other organ involvement, but this did not reach statistical significance. Most patients who had cytogenetic analysis had a diploid karyotype within their MS and bone marrow. RAS pathway mutations were enriched in MS at diagnosis, and at time of medullary relapse. Our study provides a large dataset summarizing the clinical and molecular analysis of patients with MS with <20% BM blasts and suggests that monitoring for medullary leukemia is important for early detection of relapse.

Clinically occult image revelations of fluorodeoxyglucose positron emission tomography/computed tomography in a peculiar case of sinonasal myeloid sarcoma

Myeloid sarcoma (MS) is a sparse association of acute myeloid leukemia (AML) with poor overall survival. Sinonasal involvement in MS is rarer and meagerly studied. Recent prospective studies have underlined the importance of positron emission tomography/computed tomography (PET/CT) in disease assessment and relapse detection in extramedullary (EM) AML. Herein, we report a case of MS with sinonasal, orbital, dural, breast, pleural extent of disease with sacral neural foraminal compression. Initial histopathologic and clinicoradiologic features had pointed toward lymphoma. Immunohistochemistry (IHC) on the contrary revealed MS. Although the role of IHC in asserting the diagnosis of MS is remarkable, PET/CT surpasses other modalities in early detection of EM sites of involvement, overall assessment of disease burden, targeting therapy, prognostication, and relapse recognition. Inclusion of PET/CT as a baseline imaging modality can be beneficial in tailoring patient management to improve survival and overall quality of life.

Case Report: Asymmetric Bone Marrow Involvement in Patients With Acute Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation

After allogeneic hematopoietic stem cell transplantation (allo-HSCT), acute leukemia relapse is common, and asymmetric bone marrow recurrence hasn't been reported. Because the anatomical distribution of acute leukemia clones in the bone marrow after allo-HSCT is presumed to be diffuse, bone marrow aspirations are performed in single site. The first case was a 20-year-old man who was diagnosed with acute myelomonocytic leukemia and received haploidentical allo-HSCT. Routine bone marrow biopsy of his left posterior iliac bone marrow showed 52% leukemia blasts, while the right side had 0% blasts 10 days later. The second case was a 23-year-old woman who was diagnosed with acute B lymphoblastic leukemia and received HLA-identical sibling allo-HSCT. Although 62% of blasts were found in her left iliac marrow on day +122, 0% of blasts were found on a sample obtained from the right iliac crest on day +128. Bilateral iliac bone marrow pathology and whole-body ¹⁸F-FDG PET/CT scans confirmed that the leukemic infiltration in her bone marrow was asymmetric. To our knowledge, these are the first case reports of asymmetric bone marrow infiltration of blasts in acute leukemia patients after allo-HSCT. Bilateral posterior iliac crest aspirations or ¹⁸F-FDG-PET/CT scans may help distinguish such involvement.

Myeloid sarcoma, chloroma, or extramedullary acute myeloid leukemia tumor: A tale of misnomers, controversy and the unresolved

The World Health Organization classification and definition of "myeloid sarcoma" is imprecise and misleading. A more accurate term is "extramedullary acute myeloid leukemia tumor (eAML)." The pathogenesis of eAML has been associated with aberrancy of cellular adhesion molecules, chemokine receptors/ligands and RAS-MAPK/ERK signaling. eAML can present with or without synchronous or metachronous intramedullary acute myeloid leukemia (AML) so a bone marrow evaluation is always recommended. Accurate diagnosis of eAML requires tissue biopsy. eAML confined to one or a few sites is frequently treated with local therapy such as radiotherapy. About 75-90% of patients with isolated eAML will develop metachronous intramedullary AML with a median latency period ranging from 4 to 12 months; thus, patients with isolated eAML may also be treated with systemic anti-leukemia therapy. eAML does not appear to have an independent prognostic impact; selection of post-remission therapy including allogeneic hematopoietic cell transplant (alloHCT) is typically guided by intramedullary disease risk. Management of isolated eAML should be individualized based on patient characteristics as well as eAML location and cytogenetic/molecular features. The role of PET/CT in eAML is also currently being elucidated. Improving outcomes of patients with eAML requires further knowledge of its etiology and mechanism(s) as well as therapeutic approaches beyond conventional chemotherapy, ideally in the context of controlled trials.

Extra-medullary recurrence of myeloid leukemia as myeloid sarcoma after allogeneic stem cell transplantation: impact of conditioning intensity

Myeloid sarcoma (MS) as a solid extra-medullary (EM) manifestation of acute myeloid leukemia (AML), myeloproliferative or myelodysplastic syndromes is a rare presentation of relapse after allogeneic hematopoietic stem cell transplantation (HSCT). The databases of the Departments of Hematology and Oncology of the University Hospitals of Jena and Rostock were screened for patients aged 18 years or older for onset of MS after HSCT for myeloid malignancies between 2002 and 2019. Nineteen patients with MS were identified, the majority of whom had received reduced-intensity conditioning (RIC). The median onset of MS was 425 days after HSCT and the median overall survival since MS was 234 days. Although MS is associated with a poor prognosis, three patients survived more than two years and one more than 11 years after MS onset. These results indicate that RIC protocols may be associated with a higher risk of EM relapse. Since EM relapse occurred in the presence of Graft-versus-host-disease, these observations also demonstrate the limitations of graft-versus-tumor effects after HSCT. In conclusion, occurrence of MS after HSCT is associated with a poor prognosis, as multimodal curative concepts including intensive chemotherapy and another HSCT are often not viable.

Diagnostic and Therapeutic Considerations for Extramedullary Leukemia

PURPOSE OF REVIEW

The purpose of this review is to summarize the current literature on the presentation, diagnosis, and treatment options available for extramedullary (EM) manifestations of leukemia including myeloid sarcoma (MS) and leukemia cutis (LC).

RECENT FINDINGS

Advanced imaging using 18FDG-PET/CT is an effective screening tool for EM manifestations of leukemia. The role of radiation therapy has been more clearly delineated in the treatment of both MS and LC. FDA-approved targeted agents have improved outcomes in patients with AML but have not demonstrated improvements specifically for EM; however, a checkpoint inhibitor, Ipilimumab, holds promise in impacting local control for the treatment of AML-related EM. EM manifestations of leukemia pose significant therapeutic challenges. Treatment of EM is predicated on multiple factors including the presence of concomitant bone marrow involvement, AML-risk classification, and timing of presentation at initial diagnosis or relapse following systemic therapy.

Lysyl oxidase expression is associated with inferior outcome and Extramedullary disease of acute myeloid leukemia

BACKGROUND

Lysyl oxidase (LOX) has been described as necessary for premetastatic niche formation in epithelium-derived malignancies and its expression level therefore correlates with risk of metastatic disease and overall survival. However, its role in acute myeloid leukemia (AML) has not been sufficiently analyzed.

METHODS

We investigated LOX plasma expression in 683 AML patients (age 17-60 years) treated within the prospective AML2003 trial (NCT00180102). The optimal cut-off LOX value was determined using a minimal-p-value method dichotomizing patients into a LOX-high group (> 109 ng/mL, n = 272, 40%) and a LOX-low group (≤ 109 ng/mL, n = 411, 60%).

RESULTS

Higher LOX expression was associated with lower peripheral white blood cells, lower serum LDH, and a lower frequency of FLT3-ITD and NPM1 mutations at diagnosis. Higher LOX expression was found significantly more frequently in patients with secondary AML and therapy-related AML, in patients with French-American-British M5 subtypes, and in patients with adverse-risk cytogenetics. Comparing patients in the LOX-high group and the LOX-low group revealed a 3-year overall survival (OS) of 47 and 53% (p = 0.022) and 3-year event-free survival (EFS) of 27 and 35% (p = 0.005), respectively. In the LOX-high group significantly more patients had extramedullary AML compared to the LOX-low group (p = 0.037). Combining extramedullary AML and LOX as interacting factors in a multivariate analysis resulted in an independent impact on survival for the LOX-high-extramedullary interaction for OS (HR = 2.25, p = 0.025) and EFS (HR = 2.48, p = 0.008). Furthermore, in patients with extramedullary disease (n = 59) the LOX level predicted survival. Patients within the LOX-low group had an OS of 43% and EFS of 36% as compared to the LOX-high group with an OS of 13% and EFS of 6% (p = 0.002 and p = 0.008, respectively).

CONCLUSION

We hypothesize LOX expression to be a new potential biomarker to predict outcome in AML, specifically in AML subgroups such as the prognostic heterogeneous group of AML patients with extramedullary disease.

TRIAL REGISTRATION

This retrospective study was performed with patient samples registered within the prospective AML2003 trial (NCT00180102). Patients were enrolled between December 2003 and November 2009.