Extramedullary Manifestations of Myeloid Neoplasms

From the archives of MD Anderson Cancer Center. Mesothelial/monocytic incidental cardiac excrescence with a review of the literature

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a rare benign lesion composed of monocytes and mesothelial cells that is most often encountered during cardiothoracic surgery. We describe a case in a 71-year-old man with known aortic valve stenosis who presented with gradual onset dyspnea over a few weeks, made worse with minimal exertion. A transesophageal echocardiogram revealed severe aortic stenosis and mild pericardial effusion. The patient underwent aortic valve replacement, coronary artery bypass, and amputation of the left atrial appendage. Histological examination of a 0.8 cm blood clot received along with the atrial appendage showed an aggregation of bland cells with features of monocytes associated with small strands and nodules of mesothelial cells, fat cells, fibrin and a minute fragment of bone. Immunohistochemical analysis showed that the monocytic cells were positive for CD4 and CD68 (strong) and negative for calretinin and keratin. By contrast, the mesothelial cells were positive for calretinin and keratin and negative for all other markers. In sum, the morphologic and immunohistochemical findings support the diagnosis of MICE. Based on our review of the literature, about 60 cases of MICE have been reported previously which we have tabulated. We also discuss the differential diagnosis.

Granulocytic neoplasm suggestive of primary myeloid sarcoma in 3 dogs

Myeloid sarcoma (MS) is a solid tumor of granulocytic origin with extramedullary localization. This tumor is rare in humans and animals. The diagnostic approach is heterogeneous, and the definitive diagnosis may be difficult to achieve. Primary MS has never been described as a spontaneous neoplasm in companion dogs. Two purebred and 1 mixed-breed dogs, 6- to 11-year-old, developed round cell tumors in the mediastinum, lymph nodes (LNs) and tonsils, and LNs, respectively. Granulocytic origin and exclusion of lymphoid lineage were confirmed by flow cytometry, supported by immunohistochemistry or immunocytochemistry. Pivotal to the diagnosis were positive labeling for myeloid (CD11b, CD14) and hematopoietic precursors (CD34) markers, along with negative labeling for lymphoid markers. Blood and bone marrow infiltration were not detected at initial diagnosis, excluding acute myeloid leukemia. The behavior of these tumors was aggressive, resulting in poor clinical outcomes, even when chemotherapy was attempted.

Real-world experience with venetoclax-based therapy for patients with myeloid sarcoma

BACKGROUND

The treatment of myeloid sarcoma (MS) is challenging and has not markedly improved patient prognosis. The introduction of venetoclax (VEN) has changed the treatment of MS, and venetoclax-based therapy has been described as very promising in several case reports.

METHODS

In this retrospective study, we analyzed the treatment outcomes of 14 patients with MS treated with venetoclax-based therapy at The First Affiliated Hospital of Xiamen University from January 2020 to October 2023 RESULTS: The cohort consisted of 7 (50%) women and 7 (50%) men with an average age of 37.5 years. Four patients (28.6%) had isolated MS de novo, 2 (14.2%) were diagnosed synchronously with AML, and 8 (57.2%) had isolated extramedullary relapse. The most common sites for MS in our cohort were the skin and lung, followed by the spinal canal, soft tissue, bone and kidney. Five patients were affected at more than three sites. Nine patients received VEN in combination with azacytidine, and 5 patients received VEN in combination with other agents. The median number of venetoclax therapies administered was 2 cycles (range: 1-10 cycles). A response was observed in all patients included in the study, with 8 patients (57.2%) achieving a CR and 3 patients (21.4%) achieving a PR, corresponding to an ORR (including CR and PR) of 78.6%. The median follow-up time for all patients was 13 months (range 1-44 months), and the 1 year OS for all patients was 67.7%.

CONCLUSIONS

Venetoclax-based therapy shows excellent efficacy and safety in MS patients in the "real world" at a single institution, and a corresponding prospective study is needed to verify this conclusion.

Solitary eosinophilic granulocytic sarcoma in a dog

A 6-year-old male golden retriever presented with swelling of the left upper eyelid of 2 months duration, which did not improve following a course of antibiotics. Routine serum biochemistry, complete blood count and diagnostic imaging identified no clinically significant abnormalities. The mass was surgically excised, and histopathologic examination was performed. Eosinophilic granulocytic sarcoma (GS) was diagnosed based on the results of histopathology and immunohistochemistry. This is the first report of GS affecting the eyelid of a dog.

Genetic alterations in myeloid sarcoma among acute myeloid leukemia patients: insights from 37 cohort studies and a meta-analysis

Introduction

Variations in mutation rates among acute myeloid leukemia (AML) patients with myeloid sarcoma (MS) underscore the need for a thorough examination. This meta-analysis was conducted to fill the information gap concerning mutation frequencies in AML patients presenting with MS.

Materials and methods

This study included retrospective and prospective cohorts. It examined genetic alterations in AML patients with and without MS across all age groups. The search strategy employed terms such as "acute myeloid leukemia," "extramedullary," "granulocytic sarcoma," "myeloid sarcoma," and "leukemic cutis" in the EMBASE, MEDLINE, and Scopus databases. Excluded from the study were reviews, case reports, and case series with fewer than 10 cases. Statistical analyses were performed with Review Manager 5.4 software.

Results

The primary analysis incorporated data from 37 cohorts involving 5646 diagnosed AML patients and revealed a 17.42% incidence of MS. The most prevalent mutation among AML patients with MS was FLT3-ITD, with a pooled prevalence of 17.50% (95% CI 12.60% to 22.50%; I2 82.48%). The dominant fusion gene was RUNX1::RUNX1T1, displaying a pooled prevalence of 28.10% (95% CI 15.10% to 41.20%; I2 96.39%). In comparison, no significant intergroup differences were observed for NPM1, FLT3-ITD, KIT, and IDH2 mutations. Interestingly, the CEBPA mutation exhibited protective effects for MS patients, with an odds ratio of 0.51 (95% CI 0.32 to 0.81; I2 0%). Conversely, the NRAS mutation was associated with an increased risk of MS development, with an odds ratio of 5.07 (95% CI 1.87 to 13.73; I2 0%).

Conclusion

This meta-analysis sheds light on the prevalence of genetic mutations in AML patients with MS, providing insights into the unique characteristics of the mutations and their frequencies. These discoveries are crucial in informing therapeutic and prognostic decisions for individuals with myeloid sarcoma.

The immutable relevance of myeloid sarcomas: Clinicopathological study of fourteen cases

An extramedullary myeloid tumor or chloroma is an infrequent manifestation of a myeloid neoplasm. It is considered an equivalent to an acute myeloid leukemia. It is confirmed through biopsy, where infiltrating neoplastic myeloid cells distort the parenchyma. A total of twenty-nine cases were diagnosed as MS between 198 and 2023. Upon re-evaluation, only fourteen cases fulfilled the criteria for MS. The most common differential diagnosis were lymphomas, leukemic infiltration, and extramedullary hematopoiesis. Few were isolated cases; the rest were in the context of progression of a myeloid neoplasm. The majority had a myelomonocytic morphology and immunophenotype. The most reliable markers were CD45, HLA-DR, CD68 and CD4. The study highlights the complexity and impact of an accurate diagnosis of a myeloid sarcoma.

Myeloid sarcoma presenting as fingertip necrosis with underlying suppurative tenosynovitis: A case report

We report an unusual case presentation of a patient with necrotic tissue changes of the right second and third fingers, found to have myeloid sarcoma with Staphylococcus-positive tenosynovitis and underlying acute myeloid leukemia, to highlight the importance of comprehensive evaluation in patients with atypical wounds.

Case report: The first case of concurrent breast myeloid sarcoma and borderline phyllodes tumor with malignant features

Background

Myeloid sarcoma (MS) is a rare hematological malignancy characterized by the formation of a solid mass of myeloblasts outside the bone marrow, such as in the lymph nodes, skin, or bone. MS may arise de novo or concurrently with acute myeloid leukemia (AML), myeloproliferative neoplasm (MPN), or myelodysplastic syndrome (MDS). MS accounts for less than 1% of extramedullary acute myeloid leukemia cases. Phyllodes tumors (PTs) are a rare fibroepithelial breast tumor that can be benign, malignant, or borderline, and account for less than 1% of all breast cancers.

Case presentation

We present a unique case of a 50-year-old woman with both breast MS and borderline PT with malignant features, which presented a diagnostic challenge. The patient initially presented with a mass in her right breast, and the initial fine-needle biopsy revealed the presence of immature myeloperoxidase (MPO)+ myeloid cells consistent with MS. Subsequent pathological analysis of tumor tissues after neoadjuvant radiotherapy and chemotherapy showed a borderline PT with malignant features. Following excision of the tumor, the patient experienced a local recurrence, which was also surgically removed. At 8 months post-surgery, the patient remains free of recurrence under close follow-up.

Conclusion

This case highlights the importance of considering the possibility of concurrent malignancies in the differential diagnosis of complex breast masses and underscores the challenges involved in diagnosing and managing such cases. Additionally, we also emphasize the value of neoadjuvant radiotherapy and chemotherapy in MS.

Dysphagia as an Initial Presentation of Acute Myeloid Leukemia: A Rare Presentation of Myeloid Sarcoma

Myeloid sarcoma (MS) represents a unique clinical presentation of acute myeloid leukemia (AML). This report describes a case of MS in a 66-year-old man who presented with dysphagia, nausea, vomiting, anorexia, and fatigue. Generalized lymphadenopathy was noted on physical exam and confirmed by CT scans which also showed diffuse esophageal wall thickening. Axillary lymph node biopsy was positive for MS. Bone marrow biopsy confirmed AML with 88% blasts. The patient received induction chemotherapy with decitabine and venetoclax and was planned for four cycles of treatment over three months while monitoring the response.

Myeloid sarcoma and pathological fracture: a case report and review of literature

Myeloid sarcoma is a rare clinical entity that presents as an isolated proliferation of leukemic cells, concurrently with or at relapse of acute myeloid leukemia (AML), myelodysplastic syndromes/neoplasms (MDS), chronic myeloid leukemia (CML), and myeloproliferative neoplasm (MPN). Myeloid sarcoma disrupts the normal architecture of its surrounding tissues. When it forms in long bones, it can cause their pathological fracture. We recently experienced a rare case of MDS presenting with myeloid sarcoma in the femur that eventually resulted in its pathological fracture. Detailed chromosomal analysis of the bone marrow cells suggested emergence of myeloid sarcoma during the fast-paced progression of MDS just after acquiring trisomy 22. A comprehensive review of previous cases of myeloid sarcoma-associated pathological fracture indicated possible involvement of structural rearrangements of chromosomes 9 and 22. Management of myeloid sarcoma should continue to improve, and clinicians should note that myeloid sarcoma with specific chromosomal alterations needs extra medical attention to prevent pathological fracture.

Leukostasis With Isolated Central Nervous System Involvement in Chronic Phase of Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a hematologic malignancy with unique significance to the field of hematology and oncology, specifically due to the development of tyrosine kinase inhibitors (TKIs). CML often presents with nonspecific symptoms, and the quality of life in patients with CML has drastically improved as a result of TKIs. However, complications of CML including the risk of transforming into life-threatening blast crises continue to exist. Further, as most patients are asymptomatic in the chronic phase, patients often present with serious complications associated with noncompliance to TKIs. For example, central nervous system (CNS) manifestations of CML have been reported, both as the initial presentation of undiagnosed CML and as known complication of uncontrolled CML. Hyperleukocytosis is a manifestation of uncontrolled CML and leukostasis is a complication, occurring in cases of acute myeloid leukemia (AML). Here we present a rare case of leukostasis in a patient with known CML presenting on computed tomography (CT) as intracranial masses in the chronic phase. Our goal is to discuss this rare case of leukostasis in adult CML and describe its management.

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.

Myeloid sarcoma: more and less than a distinct entity

Myeloid sarcoma (MS) is a distinct entity among myeloid neoplasms defined as a tumour mass of myeloid blasts occurring at an anatomical site other than the bone marrow, in most cases concomitant with acute myeloid leukaemia (AML), rarely without bone marrow involvement. MS may also represent the blast phase of chronic myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS). However, the clinical and molecular heterogeneity of AML, as highlighted by the 2022 World Health Organization (WHO) and International Consensus (ICC) classifications, indirectly define MS more as a set of heterogeneous and proteiform diseases, rather than a homogeneous single entity. Diagnosis is challenging and relies mainly on histopathology, immunohistochemistry, and imaging. Molecular and cytogenetic analysis of MS tissue, particularly in isolated cases, should be performed to refine the diagnosis, and thus assign prognosis guiding treatment decisions. If feasible, systemic therapies used in AML remission induction should be employed, even in isolated MS. Role and type of consolidation therapy are not univocally acknowledged, and systemic therapies, radiotherapy, or allogeneic hematopoietic stem cell transplantation (allo-HSCT) should be considered. In the present review, we discuss recent information on MS, focusing on diagnosis, molecular findings, and treatments also considering targetable mutations by recently approved AML drugs.

Bilateral adnexal masses: A case report of acute myeloid leukemia presenting with myeloid sarcoma of the ovary and review of literature

•We report a case of a patient with acute myeloid leukemia (AML) presenting as myeloid sarcoma.•This patient with bilateral adnexal masses was managed via total robotic hysterectomy with bilateral salpingo-oophorectomy.•There are a limited number of reports of bilateral ovarian occurrences that exist in the literature.•Myeloid sarcoma of the ovaries may present with vaginal bleeding to dysmenorrhea, dysuria, and palpable abdominal mass.

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.

Top Ten Lymphoproliferative Lesions Not to Miss When Evaluating Oral Ulcer Biopsies

BACKGROUND

Oral ulcers represent a full thickness loss of the mucosal epithelium leading to exposure of the submucosal connective tissue. These are common and usually self-limited lesions, although they may sometimes result from neoplasms, most commonly squamous cell carcinoma. Lymphoproliferative disorders may be difficult to diagnose in apthous ulcers since they mimic reactive inflammation.

METHODS

This review presents ten rare oral lymphoid proliferations which should not be missed when assessing oral ulcer biopsies.

RESULTS

The ten lesions include several with diagnostic cells which look similar to the histiocytes of a reactive inflammatory ulcer, including Rosai-Dorfman disease, reticulohistiocytoma, Langerhans cell histiocytosis, and traumatic ulcerative granuloma. Other lesions, such as EBV-positive mucocutaneous ulcer, extranodal marginal zone lymphoma of mucosal-associated lymphoid tissue, and plasmablastic lymphoma have lymphoid and/or plasma cell differentiation that mimic the reactive lymphocytes and plasma cells found in reactive ulcers. Two dendritic cell lesions, follicular dendritic cell sarcoma and blastic plasmacytoid dendritic cell neoplasm, both have distinct phenotypes which are required to make an accurate diagnosis.

CONCLUSION

Each of these lesions are diagnosed by evaluating their histology, along with their phenotypic profile, which is sometimes enhanced by pertinent molecular findings.

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.

Presentation of Chloromas in B-Mode Ultrasound and Contrast-Enhanced Ultrasound

Chloromas, also referred to as myeloid sarcomas, describe rare extramedullary tumor aggregates of malignant myeloid progenitor cells. The aim of this study was investigate the diagnostic features and characteristics of chloromas using contrast-enhanced ultrasound (CEUS). Between July 2007 and April 2021, 15 patients with 20 myeloid neoplasms and suspected chloroma manifestations were examined using B-mode US (B-US) and CEUS. Clinical data and B-US (echogenicity, border, size) and CEUS (hyper-, iso-, hypo- or complex enhancement) characteristics were retrospectively analyzed. Absolute and relative frequencies were determined. In B-US, the chloromas were most frequently hypo-echoic (n = 15, 75%). In addition, a hyperechoic (n = 2, 10%) or echocomplex (n = 3, 15%) presentation was observed. On CEUS, 7 chloromas (35%) had an arterial hyperenhancement, 8 (40%) an iso-enhancement and 3 (15%) a complex enhancement. Two chloromas (10%) did not exhibit any enhancement. We describe for the first time CEUS and B-US patterns of chloromas. They are typically hypo-echoic on B-US and have a strong iso- or hyperenhancement on CEUS, which may help in the differential diagnosis of some unclear masses (e.g., hematoma, abscess) in patients with myeloid neoplasias. Nevertheless, histology is necessary for a reliable diagnosis.

Clinical Characteristics and Treatment Outcomes of Myeloid Sarcoma in Children: The Experience of the Polish Pediatric Leukemia and Lymphoma Study Group

Introduction

Myeloid sarcoma (MS) is an extramedullary malignant tumor composed of immature myeloid cells. It occurs in patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or chronic myeloid leukemia (CML). MS may coincide with disease diagnosis or precede bone marrow involvement by months or even years; it can also represent the extramedullary manifestation of a relapse (1, 2).

Aim

The aim of this study is to describe clinical characteristics of children diagnosed with MS in Poland as well as to analyze diagnostic methods, treatment, and outcomes including overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS). The study also attempted to identify factors determining treatment outcomes.

Patients

The study group comprised 43 patients (F=18, M=25) aged 0-18 years (median age, 10.0 years; mean age, 8.8 years) diagnosed with MS based on tumor biopsy and immunohistochemistry or identification of underlying bone marrow disease and extramedullary tumor according to imaging findings.

Methods

The clinical data and diagnostic and therapeutic methods used in the study group were analyzed. A statistical analysis of the treatment outcomes was conducted with STATISTICA v. 13 (StatSoft, Inc., Tulsa, OK, USA) and analysis of survival curves was conducted with MedCalc 11.5.1 (MedCalc Software, Ostend, Belgium). Statistical significance was considered at p<0.05.

Results

In the study group, MS was most frequently accompanied by AML. The most common site of involvement was skin, followed by orbital region. Skin manifestation of MS was more common in the age group <10 years. The most frequent genetic abnormality was the t(8;21)(q22;q22) translocation. The 5-year OS probability (pOS), 5-year RFS probability (pRFS), and 5-year EFS probability (pEFS) were 0.67 ± 0.08, 0.79 ± 0.07, and 0.65 ± 0.08, respectively. In patients with isolated MS and those with concurrent bone marrow involvement by AML/MDS, pOS values were 0.56 ± 0.12 and 0.84 ± 0.09 (p=0.0251), respectively, and pEFS values were 0.56 ± 0.12 and 0.82 ± 0.08 (p=0.0247), respectively. In patients with and without the t(8;21)(q22;q22) translocation, pEFS values were 0.90 ± 0.09 and 0.51 ± 0.14 (p=0.0490), respectively.

Conclusions

MS is a disease with a highly variable clinical course. Worse treatment outcomes were observed in patients with isolated MS compared to those with concurrent bone marrow involvement by AML/MDS. Patients with the t(8;21)(q22;q22) translocation were found to have significantly higher pEFS. MS location, age group, chemotherapy regimen, surgery, and/or radiotherapy did not have a significant influence on treatment outcomes. Further exploration of prognostic factors in children with MS is indicated.

Coexisting Extra-Medullary Manifestation of Chronic Myelomonocytic Leukemia and Follicular Lymphoma What's Between Neoplastic Follicles Matters

We illustrate a rare case of coexisting extramedullary manifestation of CMML and new onset follicular lymphoma within the same core-needle biopsy of a lymph node. We discuss the differences between extramedullary hematopoiesis and extramedullary manifestation of myeloid neoplasms. We also highlight the importance of generous tissue sampling and thorough examination of nodal tissue in the setting of an established myeloid neoplasm to avoid missing rare but possible nodal involvement.

Target Therapy for Extramedullary Relapse of FLT3-ITD Acute Myeloid Leukemia: Emerging Data from the Field

FMS-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase family member. Mutations in FLT3, as well known, represent the most common genomic alteration in acute myeloid leukemia (AML), identified in approximately one-third of newly diagnosed adult patients. In recent years, this has represented an important therapeutic target. Drugs such as midostaurin, gilteritinib, and sorafenib, either alone in association with conventional chemotherapy, play a pivotal role in AML therapy with the mutated FLT3 gene. A current challenge lies in treating forms of AML with extramedullary localization. Here, we describe the general features of myeloid sarcoma and the ability of a targeted drug, i.e., gilteritinib, approved for relapsed or refractory disease, to induce remission of these extramedullary leukemic localizations in AML patients with FLT3 mutation, analyzing how in the literature, there is an important development of cases describing this promising potential for care.

Extramedullary Acute Leukemia-Still an Unforeseen Presentation

Myeloid sarcomas (MS) are rare extramedullary (EM) hematological tumors that generally arise during the natural course of acute myeloid leukemia (AML), occurring concomitantly with the onset of systemic leukemia; it can also occur following onset but rarely before. Common sites of EM involvement include the lymph nodes, skin, soft tissue, bone and peritoneum. Herein, we report the case of a 63-year-old man who presented EM AML upon initial diagnosis involving the bone marrow, lymph nodes and skin (leukemia cutis). A diagnosis was made based on immunohistochemistry (IHC). This case presents a diagnostic dilemma due to its atypical presentation and the sites involved. It also highlights the importance of IHC in the diagnosis of EM AML. The potential role of hypomethylating agents and Venetoclax in cases not eligible for hematopoietic stem cell transplant are also discussed.

Gastric Myeloid Sarcoma Mimicking a Scirrhous Gastric Cancer

Myeloid sarcoma (MS) is a relatively rare manifestation of myeloid neoplasms at sites other than the bone marrow. The rarity of gastrointestinal (GI) MS is attributed to certain factors, such as misdetection due to insufficient endoscopic assessments at the initial presentation with acute myeloid leukemia (AML) as well as the difficulty of making a histologic assessment of leukemic involvement of the GI tract. We herein report a case of AML with gastric involvement and discuss the importance of screening examinations and therapies considering the location of MS and the data of cytogenetic and molecular mutation.

Myeloid Sarcoma Involving the Testis in Adults: Clonal Evolution of Acute Myeloid Leukemia

To describe the clinical, histologic, immunophenotypic, and genetic characteristics of myeloid sarcoma (MS) diagnosed in the testes of adults, 3 cases were identified, and information on their presentation, clinical features, treatment, and outcome was retrieved from the medical records. In addition, histologic, immunophenotypic, and molecular characteristics were reviewed. This showed that all patients had a previous history of acute myeloid leukemia (AML), in 2 cases diagnosed >10 years before the testicular lesions. In 1 case, there was bilateral involvement, while in 2, involvement was unilateral. The neoplastic cells showed evidence of cytogenetic/molecular clonal evolution in all cases, 1 of which also had significant immunophenotypic changes. A mutational profile including NPM1 p.Trp288Cysfs*12, IDH1 p.Arg132His NRAS p.Gly12Asp was seen in 2 of the 3 cases. Concurrent bone marrow involvement by a myeloid neoplasm was diagnosed in 2 patients, in 1, there was AML in the second 8% blasts. These patients progressed rapidly after MS and had a dismal outcome. The patient with no concurrent bone marrow disease had a favorable outcome. In conclusion, MS involving the testes of adults is a rare event, and it may represent the clonal evolution of AML.

Relapsed acute myeloid leukemia presenting as conjunctival myeloid sarcoma: a case report

Background

Conjunctival myeloid sarcoma (MS) as an isolated presentation of acute myeloid leukemia (AML) relapse is rare. Here, we report a case of unilateral conjunctival MS revealed as a sign of AML relapse.

Case presentation

A 50-year-old man with a history of AML in remission visited our clinic presenting with a left conjunctival injection persisting for 1 month. Diffuse subconjunctival thickening with conjunctival vascular engorgement was observed. Ultrasound biomicroscopy revealed a hyper-reflective, thickened conjunctiva in his left eye. During the incisional biopsy, the lesion was strongly attached to the underlying sclera; histopathologic examination revealed infiltration of leukemic blasts. The relapse of AML was confirmed by a successive bone marrow biopsy. The ocular lesion disappeared after allogeneic peripheral blood stem cell transplantation (PBSCT) and concomitant salvage radiotherapy on the left eye. The patient has remained in remission for 3 years after allogeneic PBSCT.

Conclusions

Incidental conjunctival lesions can indicate AML relapse in patients treated earlier for AML. An ophthalmologist may have a role in the early detection of AML when a patient presents with an atypical conjunctival lesion.

Isolated Myeloid Sarcoma: A Diagnostic Dilemma

Myeloid sarcoma (MS)/granulocytic sarcoma/myeloblastoma/chloroma is a rare extramedullary proliferation of blast cells of one or more myeloid lineages along with the destruction of the normal architecture of adjacent tissue. Isolated MS is a rare entity with an incidence of 0.7 out of 1 million children and 2 out of 1 million adults. Varied clinical presentation, the rarity of the diagnosis, inadequate immunophenotyping, and lack of available literature makes the disease difficult to manage. Here, we report a case of MS in a 44-year-old male with an initial presentation of testicular mass without bone marrow involvement, causing diagnostic challenges. In this case report, we discuss the pathogenesis, diagnostic challenges, and therapeutic options of MS.

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.

Myeloid Sarcoma of the Testis in Children: Clinicopathologic and Immunohistochemical Characteristics With KMT2A (MLL) Gene Rearrangement Correlation

Myeloid sarcoma (MS) is defined as an extramedullary mass-forming lesion composed of immature myeloid cells. It is a rare but well-known manifestation of acute myeloid leukemia. Pediatrics testicular MS may pose a possible diagnostic challenge, an issue that is underscored in the few testicular pediatric MS cases reported in the literature. Herein, we report a series of 5 cases of pediatric testicular MS that are evaluated at the morphologic and immunohistochemical levels with correlation with the KMT2A (MLL) rearrangement status. Three patients presented with no prior history of acute myeloid leukemia. All 5 cases showed monoblastic morphology; positive for CD33, CD43, CD68, CD163, CD4 (dim), and lysozyme; and negative for CD10, CD34, CD117, and myeloperoxidase. KMT2A (MLL) rearrangement was detected in 4 of the 5 cases. In the literature, 8 more cases of pediatric testicular lymphoma were reported. Most of them showed monocytic differentiation and KMT2A (MLL) rearrangement was reported in 3 of the cases. In conclusions, testicular MS in pediatric patients shows monoblastic differentiation which may be attributed to the KMT2A (MLL) rearrangement. We also highlight the importance of using an extended immunohistochemistry panel in the diagnosis of MS.

Chronic myeloid leukemia-leukemia cutis mimicking a neutrophilic panniculitis-like leukemia cutis: Report of a rare case

While drug-induced panniculitis is not uncommon in chronic myeloid leukemia (CML) patients on tyrosine kinase inhibitor therapy, it is rare for CML to initially present as a leukemic panniculitis. We present the case of a 45-year-old male with no relevant prior medical history presenting with 6 months of migratory nodules, 2 months of drenching night sweats, and a 20 pound weight loss. Physical examination showed firm subcutaneous nodules with overlying ecchymoses present on the right lateral thigh and left lower back. Biopsy of a nodule from the right thigh showed a subcutaneous lobular panniculitis involved by a dense infiltrate of neutrophils and granulocyte precursors. Fluorescent in-situ hybridization (FISH) was positive for t(9;22)(q34;q11.2)BCR-ABL1 fusion. A concurrent hemogram revealed a white blood cell count elevation of 600,000 K/μL. Bone marrow biopsy examination showed marked myeloid expansion with an increase in granulocyte precursors and Philadelphia chromosome positivity by FISH, consistent with bone marrow involvement by CML. Herein, we describe this unusual and rare case of CML initially presenting as a neutrophilic panniculitis-like leukemia cutis. Arriving at this challenging diagnosis may be easily missed without clinical and laboratory correlation, which would certainly lead to the patient's not receiving life-saving treatment.

ZEB2 Knock-down Induces Apoptosis in Human Myeloid Leukemia HL-60 Cells

INTRODUCTION

Acute myeloid leukemia (AML) is the most prevalent type of cancer in the adult hematopoietic system. Conventional therapies are associated with unfavorable side effects in individuals diagnosed with AML. These after-effects with partial remission reflect the urgent need for novel therapeutic approaches for inducing apoptosis, specifically in malignant cells, without affecting other cells. As a transcription factor (TF), ZEB2 (Zinc Finger E-Box Binding Homeobox 2) regulates the expression of specific genes in normal conditions. However, increased expression of ZEB2 is reported in various cancers, especially in AML, which is related to a higher degree of apoptosis inhibition of malignant cells. In this work, the role of ZEB2 in apoptosis inhibition is surveyed through ZEB2 specific knocking-down in human myeloid leukemia HL-60 cells.

MATERIALS AND METHODS

Transfection of HL-60 cells was conducted using ZEB2-siRNA at concentrations of 20, 40, 60, and 80 pmol within 24, 48, and 72 h. After determining the optimum dose and time, flow cytometry was used to measure the apoptosis rate. The MTT assay was also utilized to evaluate the cytotoxic impact of transfection on the cells. The expression of candidate genes was measured before and after transfection using qRT-PCR.

RESULTS

According to obtained results, suppression of ZEB2 expression through siRNA was associated with the induction of apoptosis, increased pro-apoptotic, and decreased anti-apoptotic gene expression. Transfection of ZEB2-siRNA was also associated with reduced cell proliferation and viability.

CONCLUSION

Our study results suggest that ZEB2 suppression in myeloid leukemia cells through apoptosis induction could be a proper therapeutic method.

Myeloid sarcoma of the pancreas: A case report and literature review

INTRODUCTION

Myeloid sarcoma (MS) is an extramedullary mass, consisting of myeloid blasts with or without maturation, which efface the normal tissue architecture. It occurs mainly in lymph nodes, skin and soft tissue, testis, bone, peritoneum, and gastrointestinal tract, but rarely in the pancreas. Because their clinical courses, treatments, and prognoses are quite different, it is crucially important to distinguish between MS and pancreatic cancer.

PATIENT CONCERNS

We herein report a rare case of acute myeloid leukemia (AML) which presented with a pancreatic mass that mimicked pancreatic cancer.Diagnosis: The diagnosis of MS was established based on immunohistochemical (IHC) analysis and bone marrow examination which revealed neoplastic cells with CD34+/CD117+.

INTERVENTIONS

The patient was actively treated with chemotherapy.

OUTCOMES

After 4 cycles of chemotherapy, the lesion in pancreas was significantly reduced, and the patient is still receiving further chemotherapy.

CONCLUSION

When we encounter a patient suspected of pancreatic cancer with blood cell abnormalities and no significant increase in carbohydrate antigen 19-9 (CA19-9), we need to be aware of the possibility of pancreatic MS. Preoperative pathological biopsy and IHC are indispensable. Misdiagnosis is common if we rely solely on imaging.

Unexplained ascites caused by myeloid sarcoma with omentum involvement

A previously healthy 40-year-old male was admitted with a 10-day history of abdominal distension. Physical examinations revealed bulging flanks with a fluid wave and positive shifting dullness signs.

Clinicopathologic Features of Myelodysplastic Syndromes Involving Lymph Nodes

Lymph nodes (LNs) involved by a myelodysplastic syndrome (MDS) are rare and uncommonly biopsied. In this study, we report 6 MDS patients who underwent an LN biopsy that showed MDS, and we summarize the clinicopathologic features of this cohort. All patients presented with lymphadenopathy (generalized in 5), 5 patients had splenomegaly, and 3 patients had hepatomegaly. Histologically, the LN architecture was distorted without complete effacement. MDS cells, mostly of the myeloid lineage, produced interfollicular expansion. These myeloid cells exhibited a spectrum of maturation, and immature and atypical forms were common, including eosinophils. Scattered megakaryocytes and nucleated erythroid cells were often present. Concurrent bone marrow aspirate and biopsy specimens in these patients showed persistent/resistant MDS. Following the diagnosis of LN involvement, patients did not respond well to therapy and all died by the time of the last follow-up, with a median survival of 6.7 months (range, 4.5 to 21.6 mo). In summary, patients with MDS uncommonly develop clinically evident lymphadenopathy prompting biopsy as a result of infiltration by MDS. MDS in LNs can be subtle, showing incomplete and sometimes mild distortion of the architecture, and ancillary studies including immunohistochemical and flow cytometric immunophenotypic analysis are often needed to establish the diagnosis. These data also suggest that the emergence of lymphadenopathy attributable to MDS is associated with poor treatment response and prognosis in MDS patients and that aggressive therapy or alternative treatment regimens need to be explored in this context.

Characteristics and prognosis of pediatric myeloid sarcoma in the cytogenetic context of t(8;21)

The prognosis of myeloid sarcoma (MS) is controversial. Many reports indicated that orbital-MS has a good prognosis and is closely related to t(8;21), but the prognostic role of MS in pediatric t(8;21) AML is unclear. We retrospectively analyzed data from 127 patients with pediatric t(8;21) AML diagnosed between January 2010 and June 2018. We compared patients with (n = 30) and without MS (n = 97). The median follow-up time was 52.6 months. The proportion of t(8;21) AML patients with MS was 23.6%. Males were more likely to have MS than females. The complete remission rate after the first course of induction chemotherapy and the 3-year relapse-free survival (RFS) among patients with MS were lower than those among patients without MS (60% vs. 78.4%, p = 0.045) (68.8 ± 8.8% vs. 88.0 ± 3.4%, p = 0.004). The female sex and a higher level of RUNX1/RUNX1T1 transcripts after consolidation were risk factors for poor RFS among patients with MS. Our data showed that MS was an independent risk factor in pediatric t(8;21) AML. Close monitoring of measurable residual disease of the bone marrow and extramedullary lesions is needed to guide stratified treatment.

Haploidentical hematopoietic stem cell transplantation for patients with myeloid sarcoma: a single center retrospective study

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been regarded as a potential strategy for myeloid sarcoma (MS). The previous reports focused mainly on matched sibling donor (MSD) or matched unrelated donor (MUD) transplantation. There are no reports on haploidentical HSCT (haplo-HSCT) in MS. We retrospectively reviewed 14 MS patients who underwent haplo-HSCT. All patients achieved complete donor engraftment. The median time for neutrophil engraftment and platelet engraftment were 10 (12-21) days and 18 (8-31) days. The 100-day cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) and 3-year cumulative incidence of chronic GVHD were 37.7% (95%CI, 23.2-52.1%) and 35.7% (95%CI, 22.2-49.2%). Cytomegalovirus (CMV) reactivation was documented in 86% patients, and only one patient developed CMV pneumonia. Treatment-related mortality occurred in one (7%) patient. The 1- and 3-year cumulative incidence of relapse was 21.4% (95%CI, 11.8-31.1%) and 35.7% (95%CI, 22.4-49.0%). The probability of overall survival at 1 and 3 years was 71.4% (95%CI, 51.3-99.5%) and 64.3% (95%CI, 43.5-95.0%), respectively. The probability of disease-free survival at 1 and 3 years was 71.4% (95%CI, 51.3-99.5%) and 57.1% (95%CI, 36.3-89.9%), respectively. In conclusion, haplo-HSCT is a feasible method for patients with MS who have no MSD or MUD.

Genomic analysis in myeloid sarcoma and comparison with paired acute myeloid leukemia

Myeloid sarcoma (MS) is a rare manifestation of acute myeloid leukemia (AML) characterized by extramedullary proliferation of myeloid blasts. Owing to the rarity of MS, the clonal evolution of cell populations giving rise to MS is not well understood. To study the genomic signature of MS, we used a capture-based next-generation sequencing panel targeting 479 cancer genes to interrogate the genetic variants present in MS samples and compared their genetic profiles with their paired AML samples from a cohort of seven individuals. We identified a spectrum of single-nucleotide variants (SNVs) and a spectrum of copy number alterations in MS. Our study found that variant profiles observed in MS were generally similar to AML from the same individual, supporting the notion that these tumors are derived from a common precursor, rather than de novo tumors in a susceptible host. In addition, MS cases with a higher number of SNVs show worse clinical outcomes than MS with a lower number of SNVs. Identification of these abnormalities could potentially contribute to improved prognostic classification and identify new therapeutic targets for MS.

Clinical characteristics and management of primary granulocytic sarcoma of the oral cavity: A case report and literature review

INTRODUCTION

Granulocytic sarcoma (GS) is a commonly occurring tumor comprising immature myeloid cells, which are usually related to acute or chronic myelocytic leukemia. The tumor rarely precedes leukemia without bone marrow involvement and is called primary GS. Although primary GS can occur in any body part, the involvement of the oral cavity is uncommon.

PATIENT CONCERNS

A 49-year-old woman hospitalized at the Department of Plastic and Maxillofacial Surgery presented with a growing mass in her left maxillary hard palate dating two months back. No obvious physical findings were noted during general examination. She was diagnosed with an oral ulcer at a local clinic, and received antibiotics. However, the symptoms did not improve; the mass became bigger and painful.

DIAGNOSIS

An incisional biopsy of the oral mass was performed, the immunohistochemistry showed that the tumor cells tested positive for myeloperoxidase, CD4, BCL-2, KI-67. Bone marrow aspiration was negative for malignant cells, and the laboratory test results revealed only monocytosis. Standard bone marrow cytogenetic analysis showed a normal karyotype and leukemia-related fusion gene detection was normal. Therefore, the final diagnosis was intraoral primary GS.

INTERVENTIONS

The patient was treated with a chemotherapy regimen based on idarubicin and cytarabine arabinoside.

OUTCOMES

After 2 cycles of idarubicin and cytarabine arabinoside regimen chemotherapy, the patient achieved complete remission. The tumor was barely visible in the left maxillary hard palate. There has been no evidence of disease spread and progression after 1 year of follow-up.

CONCLUSIONS

Careful morphological and immunohistochemical analyses, correlating with clinical data are necessary to establish the diagnosis of oral primary GS. Early aggressive systemic chemotherapy can effectively relieve symptoms, significantly reducing primary GS conversion into acute myelocytic leukemia and prolonging overall survival.

Leukaemia cutis as a specific skin involvement in chronic myelomonocytic leukaemia and review of the literature: Acknowledgments

The skin involvement of myeloid leukaemia is conventionally divided into specific malignant lesions and non-specific benign lesions, and these categories are also applicable in chronic myelomonocytic leukaemia (CMML). According to the 2016 World Health Organization (WHO) classification of tumours of haematopoietic and lymphoid tissues, CMML is defined as a myeloid neoplasm with characteristics of myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPNs). As a specific cutaneous sign of extramedullary infiltration, leukaemia cutis (LC) is a rare occurrence in patients with CMML, and only approximately 89 cases have been reported in the literature thus far. The clinical features of LC are varied, and LC in CMML exhibits heterogeneous histopathologic features, with manifestations as cutaneous nodules or papules that are composed of blast cells showing either granulocytic or monocytic differentiation. Skin biopsy and further immunohistochemical examination are essential at the time of diagnosis to evaluate pathological type and determine the clinical course. Generally, once diagnosed as LC in CMML, this unusual skin lesion might be an indicator of transformation to acute myeloid leukaemia (AML) and is associated with a poor prognosis. The main treatment is allogeneic stem cell transplantation (ASCT). Therefore, early diagnosis and accurate identification have important therapeutic and prognostic significance in CMML patients with skin infiltration.

Myeloid sarcoma of the nasal cavity in a 15-month-old child: A case report

INTRODUCTION

Myeloid sarcoma (MS) is a rare tumor mass. It may occur at any extramedullary anatomic sites but is uncommon in the sinonasal location.MS commonly presents concurrently with acute myeloid leukemia (AML), but it may predate AML over several months or years, named isolated MS.

PATIENT CONCERNS

We report a case of a 15-month-old child who presented with mouth breathing, bilateral rhinorrhea, palpebral edema and proptosis. The routine blood tests were normal for the first few months. Computed tomography scan revealed neoplasm in nasal cavity.

DIAGNOSIS

The patient was definitely diagnosed with isolated MS in the nasal cavity through immunohistochemistry combined with clinical features and radiological investigations, and MS further progressed to AML which was confirmed by hematologist.

INTERVENTIONS

Endoscopic sinus surgery was performed to acquire specimens. After diagnosis, the patient was promptly treated with systemic chemotherapy.

OUTCOMES

All symptoms gradually subsided and the mass of nasal cavity was invisible. No relapse occurred during follow-up.

CONCLUSION

Sinonasal MS may be misdiagnosed and should be considered when symptoms persist and worsen. Prompt clinic examinations are essential for cases with suspected MS. Diagnosis of MS is dependent on the immunohistological investigations combined with clinical features, radiological investigations. Early diagnosis and systemic chemotherapy are vital for patients to achieve best prognosis.

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.

Myeloid diseases in the lung and pleura

Myeloid diseases detected as primary or secondary lesions in the lung and pleura are rare. Clinical presentations and radiographic results may vary significantly depending on the nature of the diseases. The most common diseases associated with lung and pleura involvement are myeloid sarcoma/acute myeloid leukemia (AML) and extramedullary hematopoiesis (EMH). AML typically represents localized involvement by systemic acute leukemia, while EMH is frequently secondary to underlying benign hematolymphoid disorders or myeloproliferative neoplasms. This review provides an overview of the pathogenesis, clinical presentations, radiologic/imaging studies, pathologic and genetic findings, and treatment/outcomes associated with myeloid diseases in the lung and pleura.

Pediatric thoracic mass lesions: Beyond the common

Thoracic mass lesions can be categorized as originating in one of the three major compartments: a) chest wall and pleura, b) lung parenchyma and airways, c) mediastinum. While some of these, such as lymphoma, are common in both children and adults, others are rare and unique to childhood. The goal of this review is to familiarize radiologists with unusual but distinctive mass lesions of the pediatric thorax.

Myeloid sarcoma

PURPOSE OF REVIEW

Myeloid sarcoma; also known as granulocytic sarcoma and chloroma, often occurs concomitantly with AML, and rarely without bone marrow involvement. In this article, we review the recent literature on myeloid sarcoma, focusing on treatment approach for this rare disease, and addressing the prognostic and therapeutic role of molecular and cytogenetic aberrations.

RECENT FINDINGS

Molecular testing and cytogenetics are important adjunct to conventional diagnostic methods. The significance of cytogenetic and molecular abnormalities in myeloid sarcoma is not completely established, but testing for targetable mutations on myeloid sarcoma cells is feasible, imperative, and may guide treatment decisions. Outcomes in myeloid sarcoma largely depend on the background of its development. Almost all patients with myeloid sarcoma eventually develop AML typically in a short period after its diagnosis; therefore, remission induction treatment using AML type chemotherapy has been the standard of care. Postremission therapy is controversial; allogenic SCT, radiotherapy or consolidation chemotherapy should be considered according to patient risk.

SUMMARY

Further research is required to understand the nature of myeloid sarcoma, and inclusion of patients with this condition in clinical trials should be considered to better identify the best diagnostic, prognostic, and therapeutic approach in managing this rare disease.

Leukemic Involvement in the Thorax

Leukemias are malignancies in which abnormal white blood cells are produced in the bone marrow, resulting in compromise of normal bone marrow hematopoiesis and subsequent cytopenias. Leukemias are classified as myeloid or lymphoid depending on the type of abnormal cells produced and as acute or chronic according to cellular maturity. The four major types of leukemia are acute myeloid leukemia, chronic myeloid leukemia, acute lymphoblastic leukemia, and chronic lymphocytic leukemia. Clinical manifestations are due to either bone marrow suppression (anemia, thrombocytopenia, or neutropenia) or leukemic organ infiltration. Imaging manifestations of leukemia in the thorax are myriad. While lymphadenopathy is the most common manifestation of intrathoracic leukemia, leukemia may also involve the lungs, pleura, heart, and bones and soft tissues. Myeloid sarcomas occur in 5%-7% of patients with acute myeloid leukemia and represent masses of myeloid blast cells in an extramedullary location. ^©RSNA, 2019.

Integrin α7 and Extracellular Matrix Laminin 211 Interaction Promotes Proliferation of Acute Myeloid Leukemia Cells and Is Associated with Granulocytic Sarcoma

Acute myeloid leukemia (AML) with granulocytic sarcoma (GS) is characterized by poor prognosis; however, its underlying mechanism is unclear. Bone marrow samples from 64 AML patients (9 with GS and 55 without GS) together with AML cell lines PL21, THP1, HL60, Kasumi-1, and KG-1 were used to elucidate the pathology of AML with GS. RNA-Seq analyses were performed on samples from seven AML patients with or without GS. Gene set enrichment analyses revealed significantly upregulated candidates on the cell surface of the GS group. Expression of the adhesion integrin α7 (ITGA7) was significantly higher in the GS group, as seen by RT-qPCR (p = 0.00188) and immunohistochemistry of bone marrow formalin-fixed, paraffin-embedded (FFPE) specimens. Flow cytometry revealed enhanced proliferation of PL21 and THP1 cells containing surface ITGA7 in the presence of laminin 211 and stimulated ERK phosphorylation; this effect was abrogated following ITGA7 knockdown or ERK inhibition. Overall, high ITGA7 expression was associated with poor patient survival (p = 0.0477). In summary, ITGA7 is highly expressed in AML with GS, and its ligand (laminin 211) stimulates cell proliferation through ERK signaling. This is the first study demonstrating the role of integrin α7 and extracellular matrix interactions in AML cell proliferation and extramedullary disease development.