A 23-year-old man with a history of Ph-Like B-cell acute lymphoblastic leukemia (B-ALL) with JAK2 rearrangement presented with innumerable skin lesions developing over 1 week. Before presentation, he had multiple relapses of his B-ALL and underwent autologous UCD-19 chimeric antigen receptor (CAR) T-cell therapy. Lesions appeared 1.5 months after completion of therapy. Biopsies showed new onset myeloid sarcoma (MS), with continued remission of B-ALL. 18 F-FDG PET/CT showed numerous markedly hypermetabolic soft tissue lesions located in the skin and subcutaneous tissues, muscles, osseous structures, mucosa, pleura, mediastinum, peritoneum, retroperitoneum, and testes.

The diagnosis of myeloid neoplasms with plasmacytoid dendritic cell (pDC) differentiation can be challenging due to immunophenotypic overlap requiring detailed characterization by flow cytometry and immunohistochemistry. We describe two patients with a history of myeloproliferative neoplasm (MPN) and myelodysplastic/myeloproliferative neoplasm (MDS/MPN) who presented years later with leukocytosis, lymphadenopathy, splenomegaly, and cachexia, with rapid clinical deterioration and death. Lymph node biopsy specimens revealed involvement by myeloid sarcoma with prominent pDC differentiation. Furthermore, concomitant bone marrow aspiration and biopsy showed involvement by the underlying myeloid neoplasm but no parallel expansion of pDC, as seen in the lymph node specimens, suggesting that pDC differentiation is fostered in the lymph node microenvironment. These two cases could represent the "myeloid sarcoma" counterpart of the recently described acute myeloid leukemia with pDC differentiation (pDC-AML). Although patients with pDC-AML have an inferior outcome when treated with conventional therapies, the recognition of a pDC component in these neoplasms potentially expands the therapeutic options.

Acute myeloid leukemia with CBFA2T3::GLIS2 fusion can initially present as extramedullary lesions (myeloid sarcoma), leading to a misdiagnosis of nonhematologic pediatric solid tumors.

We characterized the clinicopathologic features of 4 cases of CBFA2T3::GLIS2 fusion-positive myeloid sarcoma in pediatric patients where the sarcoma presented either without leukemic involvement (isolated myeloid sarcoma; 3/4 [75%]) or had concurrent leukemic disease (1/4 [25%]).

All cases mimicked nonhematopoietic tumors at morphologic and immunophenotypic levels, so the initial evaluation did not raise suspicion for acute myeloid leukemia/myeloid sarcoma. After extensive workup, however, including molecular studies, the diagnosis of myeloid sarcoma with CBFA2T3::GLIS2 fusion was rendered.

This study highlights the need for a high suspicion index of GLIS2-rearranged myeloid sarcoma in the differential diagnosis of pediatric small round cell tumors in tissue biopsies and the application of adequate workup to avoid misdiagnosing this entity.

Myeloid sarcoma (MS) is a rare hematological neoplasm with poor prognosis, posing a significant clinical challenge due to the absence of effective and standardized treatments. We conducted a retrospective analysis of 162 MS patients treated at 12 centers to compare outcomes between intensive chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our analysis revealed that allo-HSCT demonstrated superior overall survival (OS) within the initial 36 months compared to intensive chemotherapy alone (p = 0.037). However, beyond 36 months (36-60 months), a reverse trend was observed (p = 0.056). Subgroup analysis revealed potential benefit for isolated MS patients with allo-HSCT, but not for those with leukemic MS. Additionally, in patients achieving first complete remission (CR1) after induction chemotherapy, allo-HSCT did not significantly improve 5-year OS compared with intensive chemotherapy alone (p = 0.25). Conversely, allo-HSCT significantly improved 5-year OS in non-CR1 patients (p < 0.001). Notably, HLA-matched HSCT and haploidentical HSCT showed comparable outcomes in terms of OS, disease-free survival, and cumulative incidence of relapse. In conclusion, allo-HSCT improved outcomes for MS patients within 36 months of disease onset, and haploidentical HSCT emerged as a viable treatment option for patients without matched donors.

Acute myeloid leukemia (AML) can infiltrate extramedullary tissues, such as the liver, spleen, and lymph nodes and can be difficult to differentiate from lymphoma in cytologic and histologic specimens. Our goal was to identify cytologic features that would support a diagnosis of AML in peripheral lymph node aspirates, for which we used the term extramedullary AML (eAML). Medical records of 23 dogs with a diagnosis of AML and archived lymph node aspirate smears from 2016 to 2024 were reviewed across 4 institutions. Inclusion criteria included ≥50% myeloid blasts plus differentiating myeloid cells in lymph node smears, confirmation of myeloid lineage by flow cytometric analysis, and complete medical records. Peripheral lymphadenopathy was the reason for presentation (9/23, 39%) or was found incidentally on physical examination (14/23, 61%). Most dogs were bi- or pancytopenic (18/23, 78%), with blasts identified in blood smears of 18 dogs (78%). Initial lymph node aspirate interpretations included hematopoietic neoplasia (8/21, 38%), AML (6/21, 29%), lymphoma (5/21, 24%), lymphoid hyperplasia (1/21, 5%), and granulocytic precursor infiltrates (1/21, 5%). On lymph node smear review, cytologic features supporting an eAML were differentiating granulocytes, blasts with myeloid features or promonocytes, dysplastic changes in myeloid cells, and retention of residual lymphocytes. The median survival was 22 days (range = 1-360 days), and 69% of 16 dogs given chemotherapy or glucocorticoids lived for 30 days or more. Our study highlights the importance of hemogram results and lymph node aspirate smear examination for morphologic features of myeloid differentiation to help diagnose eAML in lymph node smears.

A 28-year-old male patient with a history of acute myeloid leukemia, who was in complete remission for 18 months after allogeneic peripheral blood stem cell transplantation (PBSCT), developed a salmon-pink nodular lesion of the upper bulbar conjunctiva with conjunctival vascular engorgement of the right eye, accompanied by severe anterior uveitis and hypopyon. Ocular granulocytic sarcoma (OGS) was diagnosed based on immunohistochemistry analysis of the tissue sample and flow cytometry analysis of the aqueous humour, representing a local recurrence of acute myeloid leukemia. Systemic and central nervous system infiltration was excluded. Targeted radiotherapy of the right eye (24 Gy/12 cycles) and a series of 12 intracameral injections of methotrexate (400 μg/0.1 ml) were implemented with no impact on the endothelial cell count or corneal morphology. Complete macroscopic and cytometric remission of the lesion was achieved without leaving any permanent visual defects.

Granulocytic sarcoma (GS), or myeloid sarcoma or chloroma, is a tumoral mass containing myeloblasts and immature granulocytes in an anatomic site other than the bone marrow. GS is very rare in children with acute promyelocytic leukemia (APL). This case report presents a rare case of GS manifesting as a solitary bone mass.

A 15-year-old female presented with left knee pain. Complete blood count and biochemistry were normal. No blasts or early granulocytic elements were observed in the peripheral blood smear. Magnetic resonance imaging (MRI) revealed a 4x4-cm solid lesion extending to the physis line in the distal metaphyseal section of the left femur. A Tru-cut biopsy of the mass confirmed GS with immature promyelocytic cell infiltration containing Auer rods and immature myeloid cells. The t(15;17) mutation was highly positive in the tissue suspension. Bone marrow aspiration performed afterward showed no abnormalities, and acute myeloid leukemia and acute lymphoblastic leukemia mutation panels were negative. The patient was diagnosed as having APL presenting as GS of isolated femoral origin. Treatment with standard-risk chemotherapy, including all-trans retinoic acid (ATRA) according to the BFM 2013 protocol, was initiated. After 2 months, a repeat biopsy showed no pathologic promyelocytic infiltration and a negative t(15;17) mutation. However, the patient died of severe neutropenia, sepsis, and typhoid fever.

This case contributes to the literature as a rare presentation of APL as isolated femoral GS. It is the first reported case of an isolated femoral mass in this context to the best of our knowledge.

Myeloid sarcoma (MS), or extramedullary acute myeloid leukaemia tumour (eAML), is a rare hematopoietic neoplasm. Recognised as a distinct entity within acute myeloid leukaemia (AML), MS presents significant diagnostic challenges due to its rarity, clinical heterogeneity, and variable immunophenotypic and genetic characteristics. The mechanisms by which leukaemic stem cells (LSCs) migrate to form solid tumours in extramedullary (EM) sites remain unclear. MS can occur de novo, precede AML, and manifest alongside AML relapse. It can also develop with myelodysplastic syndromes (MDSs) or myeloproliferative neoplasms (MPNs). MS frequently presents in organs such as the skin, lymph nodes, gastrointestinal (GI) tract, and central nervous system (CNS), often resulting in diverse clinical manifestations. Diagnosis relies on a comprehensive approach, including tissue biopsy, bone marrow (BM) evaluation, and advanced imaging modalities. Accurate diagnosis is crucial for risk stratification and treatment selection. Prognosis is influenced by several factors: MS's anatomical location, timing of MS diagnosis, genetic profile, and possible treatment. This review emphasises the need for comprehensive diagnostic methods to better define individual MS characteristics and prognosis. It explores the role of novel targeted therapies in improving patient outcomes and further highlights the critical need for future multicentre data collection to optimise diagnostic and therapeutic approaches.

Burkitt lymphoma is a mature aggressive B-cell neoplasm with distinctive clinical and morphologic features, a germinal center B-cell immunophenotype, a high proliferation index and MYC rearrangement with an immunoglobulin gene partner. Initially described in equatorial Africa by a surgeon, Denis Burkitt, African (endemic) Burkitt lymphoma was the first neoplasm shown to be associated with a virus, Epstein-Barr virus (EBV), and the first neoplasm shown to be associated with a chromosomal translocation, IGH::MYC. In this article, we provide a brief historical introduction of Burkitt lymphoma, followed by a review of all aspects of this neoplasm including pathogenesis, clinical presentation, morphology, immunophenotype, cytogenetics and molecular findings. We also provide recent updates of this entity, including advances in our understanding of molecular pathogenesis of Burkitt lymphoma and the recent proposal in the current World Health Organization classification that the traditional epidemiologic variants of Burkitt lymphoma are better replaced by presence or absence of EBV infection. We also discuss the differential diagnosis of Burkitt lymphoma and how this neoplasm can be distinguished from reactive conditions and other aggressive B-cell lymphomas/leukemias. Given its very rapid growth and the unique treatment approach employed to treat these patients, it is important to recognize Burkitt lymphoma to facilitate appropriate therapy.

Acute promyelocytic leukemia (APL) presenting solely as myeloid sarcoma (MS) is extremely rare. This report describes a 53-year-old male who presented with low back pain and a movement disorder in his lower limbs. MRI and PET/CT scans of the lumbar spine revealed an intraspinal mass. Pathological analysis of the surgically resected mass identified it as myeloid in origin. Routine blood tests were unremarkable, and bone marrow smears and immunophenotyping showed no evidence of abnormal myeloblasts or promyelocytes. However, bone marrow aspirates testing for acute leukemia fusion genes by qPCR revealed the presence of the PML::RARA fusion. Further investigation via FISH confirmed the fusion in both the bone marrow and the extramedullary mass. The patient was ultimately diagnosed with isolated promyelocytic extramedullary sarcoma (MS/APL). Treatment with all-trans retinoic acid and arsenic trioxide alleviated the back pain and restored the patient's mobility. After 1 year of consolidation therapy, bone marrow smears confirmed sustained remission, and the PML::RARA fusion gene was undetectable. In addition to this case, we review 41 other APL patients with extramedullary sarcoma as their first symptom (MS/APL) at the time of diagnosis and provide an analysis of these cases.

Myeloid sarcoma (MS) is a rare hematological malignancy characterized as an extramedullary tumor mass of neoplastic myeloid blasts that may involve various anatomical sites and affect their tissue structure. Given that MS is very rare, there is insufficient knowledge regarding its clinical features and no well-established therapeutic guidelines. We conducted a retrospective study of MS patients diagnosed between 2000 and 2016 using the Surveillance, Epidemiology, and End Results (SEER) database. We studied survival outcomes across different demographic and therapeutic subgroups. We also investigated the causes of death among our aimed cohort of patients. We found that between 2000 and 2016, 573 MS cases were reported in SEER 17 registries. Most patients were males (57.9%), and 55.1% were 60 or older. Most were non-Hispanic white (67.7%) and married (47.8%). Almost 61.4% were diagnosed with MS as their first primary tumor and 51.3% had only 1 tumor. In terms of treatment, 51.1% received chemotherapy, 26.2% underwent radiation therapy, and 13.6% had surgical management. The relative survival rate for MS patients in the United States is quite low, with a 3-year relative survival rate of 43.4%, declining to 39.0% at 5 years. Treatment with chemotherapy or surgical management has shown better survival outcomes. The primary cause of death is malignant diseases, particularly leukemias. Most deaths occur within the first year of diagnosis, with the risk gradually declining over time. MS is a rare malignant disease with a poor prognosis. Age and tumor location at diagnosis are important factors affecting survival. Chemotherapy is the most common treatment and has been found to improve survival. Most deaths in MS cases are due to malignant diseases, particularly leukemias. Future prospective studies are required to provide more significant outcomes and create targeted management regimens to enhance survival.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy composed of immature cells that exhibit plasmacytoid dendritic cell (pDC) differentiation. The diagnosis of BPDCN is often challenging due to its rarity and morphologic and phenotypic overlap with other hematologic malignancies, such as acute myeloid leukemia (AML). The emergence of tagraxofusp, a CD123-directed cytotoxin, and other novel therapies has underscored the importance of accurately diagnosing BPDCN. This review initially outlined the clinical and histopathological features of BPDCN, including patients with immunoblastoid morphology. Various proposed diagnostic criteria based on flow cytometry and immunohistochemistry findings were presented, highlighting critical points of caution in the diagnostic process. Strategies for detecting minimal residual disease or microinvasion in BPDCN, a significant clinical issue, were also discussed. Additionally, we reviewed the recurrent 8q24 (MYC) and MYB rearrangements observed in BPDCN, which can aid in diagnosis. Furthermore, we explored mature plasmacytoid dendritic cell proliferation (MPDCP) associated with myeloid neoplasm, which is characterized by a clonal proliferation of pDCs in cases with a defined myeloid neoplasm and may also serve as a potential differential diagnosis for BPDCN. Lastly, we discussed pDC-AML, characterized by pDC proliferation in AML cases, which can also be part of MPDCP and is often associated with frequent RUNX1 mutations. Overall, this review provides insights into BPDCN diagnosis and highlights the current challenges in its detection and differential diagnosis.

Myeloid sarcoma (MS) is an extramedullary localization of immature granulocyte cells that can occur in association with acute myeloid leukemia (AML). Gastrointestinal involvement is relatively common in MS, but exclusive colonic localization is a rare occurrence. Here, we report on a 53-year-old male patient affected by AML developing a severe abdominal pain caused by intestinal perforation requiring surgical intervention. The post-mortem examination revealed an infiltrate consistent with MS. Diagnosis of colonic MS can be difficult due to non-specific symptoms and complicated by the challenges associated with exploring this area. Clinical acumen is crucial to promptly establish adequate management due to the potentially life-threatening nature of this condition.

Myeloid sarcoma (MS) is a rare extramedullary tumor originating from immature bone marrow cells. MS of the breast is an extremely uncommon disease with non-specific clinical and radiological features. The present case report describes a distinctive case of MS of the breast, which posed diagnostic challenges due to the absence of typical imaging characteristics at the time of presentation. The patient was a 58-year-old woman who presented with a breast mass. Further examination and testing confirmed the diagnosis of MS in the right breast, with metastases to the right iliac, pubic and ischial regions. Immunohistochemical analysis identified metastatic tumors distinguished by the expression of a number of markers, including Ki-67, myeloperoxidase and cluster of differentiation 43. The patient underwent six cycles of chemotherapy with a regimen comprising etoposide, methylprednisolone, cytarabine and cisplatin, and 28 cycles (56 cGy each) of consolidation radiotherapy. Extensive examination and long-term follow-up revealed no further tumor recurrence or metastasis. Myeloid sarcomas of the breast typically manifest as palpable masses requiring diagnostic imaging. However, due to the rarity of MS of the breast without any signs of leukemia, its diagnosis and treatment are challenging. The present case report highlights the importance of maintaining high clinical, radiological and pathological standards when diagnosing this disease. Additionally, a comprehensive review of the literature on breast MS is provided. This highlights the necessity for clinicians to consider this rare diagnosis in patients presenting with a breast mass, to facilitate the appropriate treatment and prevent unnecessary procedures such as mastectomies.

Myeloid sarcoma (MS) is a proliferation of immature myeloid cells that occurs extramedullary, often accompanying acute myeloid leukemia (AML). It typically presents in areas such as lymph nodes, skin, and the head and neck regions. The emergence of MS within the temporal bone is rare, and it can manifest through nonspecific symptoms. In this paper, we reported a case of A 47-year-old female presented with right-sided otalgia, otorrhea, tinnitus, reduced hearing, and ear fullness, and developed facial asymmetry. She was initially diagnosed with necrotizing otitis externa and was treated accordingly. Further investigations were conducted, leading to the diagnosis of MS. She began treatment with induction chemotherapy followed by consolidation therapy. And we reviewed the literature and included 14 MS cases with the same anatomical localization, discussing the primary presentation, immunohistochemistry, and treatment approaches of these patients. In conclusion, temporal bone MS should be considered in patients with a history of AML presenting with nonspecific symptoms. Diagnostic modalities for MS include computed tomography and magnetic resonance imaging scans. Systemic chemotherapy remains the preferred treatment approach. The complexity and diversity of temporal bone MS presentations necessitate further comprehensive research to enhance understanding and improve management strategies for this rare condition.

Myeloid sarcoma (MS) occurs when primitive or naive myeloid cells form outside the bone marrow. It occurs mainly in soft/connective tissue and skin; orbital involvement is rare. We report the cases of two female adults, analyze the clinicopathologic characteristics, and review the literature. The average age of both patients was 28 years and they presented unilateral proptosis combined with varying degrees of impaired visual acuity and restricted ocular motility in the affected eye. Despite this, they maintained good overall health and no notable family history. However, the patients had no systemic clinical manifestations of acute myeloid leukemia (AML). Both patients underwent surgical resection of the orbital tumor. Immunohistochemistry showed positive staining for CD43, Leukocyte Common Antigen (LCA), and myeloperoxidase (MPO) and a high level of positive staining for Ki67, which were diagnostic for MS. Bone marrow cytology examination showed no apparent abnormalities. Postoperative chemotherapy, local radiotherapy, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) were performed in Case 1, while the second patient underwent adjuvant chemotherapy and radiotherapy. No recurrence or metastasis was found in either patient during follow-up (one more than 5 years, the other more than 10 years). The occurrence of orbital MS is infrequent, with atypical clinical and imaging findings. The diagnosis depends on pathomorphology and immunohistochemical staining, and the prognosis is good with postoperative adjuvant chemotherapy, local radiotherapy, and allo-HSCT.

Granulocytic sarcoma (GS) or myeloid sarcoma (MS) is a tumor of hematopoietic stem cell origin composed of myeloblasts or immature myeloid cells presenting as tumor masses in an extramedullary site. The tumor can affect any site of the body but are commonly seen in the skin, bone and lymph node. It may develop de novo or concurrently with acute myeloid leukemia (AML), myeloproliferative disorder (MPD) or myelodysplastic syndrome (MDS). MS may precede AML by months or years or present as an initial manifestation of relapse in a previously treated AML in remission. On light microscopic examination, based on histological features cases of MS are frequently erroneously diagnosed, more so in non-leukaemic patients, as non-Hodgkin lymphoma (NHL) or undifferentiated carcinoma. Immunophenotyping is needed for a diagnosis of MS. A variety of chromosomal abnormalities are reported; particularly t(8;21)(q22;q22), which is regarded as a recurrent aberration in MS. Only a few cases of MS of the small intestine in non-leukaemic patients, defined by the absence of a history of leukemia, myelodysplastic syndrome (MDS), or myeloproliferative neoplasm along with a negative bone marrow biopsy, are described in literature. Treatment strategies are still not well defined.

We analyse and describe 3 cases of patients with MS involving the intestine and describe the histological diagnostic pointers, clinicopathologic and immunophenotypic features.

Granulocytic sarcoma has definite well recognisable diagnostic features. The characteristic features include: tumor cells arranged in sheets and in occasional infiltrating singles; absence of necrosis; starry-sky appearance; scattered eosinophils & promyelocytes; tumor cells negative for CD3, CD20, while being positive for CD45 (patchy) and CD19.

Granulocytic sarcoma is a rare disease and a high index of suspicion is needed for making a correct diagnosis. Judicious use of immunohistochemistry helps in coming to a diagnosis. We propose a diagnostic algorithm for making a diagnosis of granulocytic sarcoma.

Granulocytic sarcoma (GS), also known as extramedullary myeloid tumor, is a rare malignant neoplasm composed of immature myeloid cells. Although it is most commonly associated with acute myeloid leukemia (AML), a subset of GS cases can occur prior to the development of AML. GS can present in a variety of extramedullary locations, including bone, skin, lymph nodes, and the female reproductive system. We report the case of a 45-year-old Asian female patient who presented to our hospital in July 2015 with a three-month history of left-sided lumbago. A contrast-enhanced computed tomography (CT) scan of the abdomen and pelvis revealed a retroperitoneal mass and an enlarged uterine cervix with an accompanying 57×52 mm mass. A cervical biopsy confirmed the diagnosis of GS. Immunohistochemical (IHC) analysis of the biopsy showed that the neoplastic cells were positive for CD34, CD15, CD33, CD43, lysozyme, and myeloperoxidase. The patient was subsequently treated with an idarubicin and cytarabine-based regimen for four cycles. A follow-up CT scan of the abdomen and pelvis demonstrated a significant reduction in the size of the previous lesions. Unfortunately, the patient passed away in April 2016 due to a cerebral hemorrhage. In this report, we also review 42 additional cases to discuss the pathological characteristics, treatment strategies, and clinical outcomes of GS.

Myeloid sarcomas (MS) comprise rare extramedullary manifestations of myeloid neoplasms with poor patients' outcome. While the clinical relevance of the tumor microenvironment (TME) is well established in many malignancies, there exists limited information in MS.

The expression of the human leukocyte antigen class I (HLA-I) antigens, HLA-I antigen processing and presenting machinery (APM) components and the composition of the TME of 45 MS and paired bone marrow (BM) samples from two independent cohorts were assessed by immunohistochemistry, multispectral imaging, and RNA sequencing (RNAseq).

A significant downregulation of the HLA-I heavy chain (HC; 67.5%) and ß2-microglobulin (ß2M; 64.8%), but an upregulation of HLA-G was found in MS compared to BM samples, which was confirmed in a publicly available dataset. Moreover, MS tumors showed a predominantly immune cell excluded TME with decreased numbers of tissue infiltrating lymphocytes (TILs) (9.5%) compared to paired BM (22.9%). RNAseq analysis of a subset of 10 MS patients with preserved and reduced HLA-I HC expression revealed 150 differentially expressed genes and a significantly reduced expression of inflammatory response genes was found in samples with preserved HLA-I expression. Furthermore, low HLA-I expression and low TIL numbers in the TME of MS cases were linked to an inferior patients' outcome.

This study demonstrated a high prevalence of immune escape strategies in the pathogenesis and extramedullary spread of MS, which was also found in patients without evidence of any BM pathology, which yields the rational for the development of novel individually tailored therapies for MS patients.

Myeloid sarcoma (MS) represents a neoplastic proliferation characterized by immature myeloid precursor cells. Among its variants, aleukemic MS is an uncommon subtype, manifesting as skin involvement sparing the peripheral blood or bone marrow. The non-specific cutaneous presentation coupled with the lack of associated symptoms poses a diagnostic challenge for providers. In this report, we present a case of an 83-year-old woman who presented with violaceous nodules located in the center of her right shin. A biopsy of the lesion unveiled a diagnosis of MS, yet notably lacked peripheral blood involvement. Three months after the initial diagnosis, the MS was found in the common bile duct, still without bone marrow involvement. With a relatively poor prognosis, the rapid diagnosis and treatment of MS are crucial.

Despite improved outcomes in newly diagnosed pediatric AML, relapsed disease remains a therapeutic challenge. Factors contributing to slow progress in improving outcomes include inherent challenges in pediatric clinical trial accrual and the scarcity of novel targeted/immunotherapy agents available for pediatric development. This paradigm is changing, however, as international collaboration grows in parallel with the development of promising targeted agents. In this review, we discuss the therapeutic landscape of relapsed pediatric AML, including conventional chemotherapy, targeted therapies, and the challenges of drug approvals in this patient population. We highlight current efforts to improve communication among academia, industry, and regulatory authorities and discuss the importance of international collaboration to improve access to new therapies. Among the therapeutic options, we highlight the approach to second hematopoietic stem cell transplant (HSCT) and discuss which patients are most likely to benefit from this potentially curative intervention. Importantly, we acknowledge the challenges in providing these high-risk interventions to our patients and their families and the importance of shared communication and decision making when considering early-phase clinical trials and second HSCT.

Myeloid sarcoma (MS) is an uncommon localized extramedullary tumor composed of immature myeloid precursor cells that can affect any organ. Promyelocytic sarcoma (PS), an extremely rare subtype of MS, is characterized by immature myeloid cells with features of acute promyelocytic leukemia (APL). We describe a case of pediatric PS that presented as a solitary sacral mass without any evidence of systemic or bone marrow involvement. The cytopathologic evaluation using touch imprint demonstrated numerous blasts with bilobed nuclei, cytoplasmic hyper-granularity, and aggregates of Auer rods, which are typical cytomorphologic features of APL. Herein, we report an extremely rare case of isolated PS in a child, emphasizing the importance of cytomorphologic evaluation, which is complemented by the findings from a comprehensive work-up.

Myeloid sarcoma, a rare extramedullary manifestation of acute myeloid leukemia (AML), can occur in various anatomic sites but seldom involves the gastrointestinal tract. We report the unusual case of a 49-year-old man with a history of AML who initially presented with abdominal pain and imaging findings suggestive of a paracolic abscess. However, the lesion rapidly progressed to a large descending colon mass with peritoneal involvement over five weeks. Surgical resection and histopathological examination confirmed a diagnosis of myeloid sarcoma. This case highlights the potential of myeloid sarcoma to mimic an inflammatory colonic process at initial presentation prior to manifesting as an overt mass lesion. Although exceedingly rare, myeloid sarcoma should be considered in patients with a history of AML presenting with colon lesions, particularly in those with an aggressive clinical course. Early recognition may expedite appropriate treatment and prevent unnecessary procedures. This report also underscores the importance of correlating imaging findings with clinical history and histopathology findings to establish an accurate diagnosis.

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.

Leukemia circulates in the bloodstream and induces various symptoms and complications. Occasionally, these cells accumulate in non-marrow tissues, forming a tumor-like myeloid sarcoma (MS). When the blast-stage leukemia cells invade the brain parenchyma, intracranial MS occurs, leading to a challenging prognosis owing to the limited penetration of cytostatic drugs into the brain and the development of drug resistance. The scarcity of tissue samples from MS makes understanding the phenotypic changes occurring in leukemia cells within the brain environment challenging, thereby hindering development of effective treatment strategies for intracranial MS. This study presents a novel 3D in vitro model mimicking intracranial MS, employing a hydrogel scaffold derived from the brain-decellularized extracellular matrix in which suspended leukemia cells are embedded, simulating the formation of tumor masses in the brain parenchyma. This model reveals marked phenotypic changes in leukemia cells, including altered survival, proliferation, differentiation, and cell cycle regulation. Notably, proportion of dormant leukemia stem cells increases and expression of multidrug resistance genes is upregulated, leading to imatinib resistance, mirroring the pathological features of in vivo MS tissue. Furthermore, suppression of ferroptosis is identified as an important characteristic of intracranial MS, providing valuable insights for the development of targeted therapeutic strategies.

Osteolytic lesions are infrequently observed in adult patients with acute myeloid leukemia (AML). This report details the case of a 66-year-old male patient who presented with myeloid sarcoma (MS), osteolytic lesion and pancytopenia. Effective treatments were delayed due to diagnostic challenges and the rapid progression of the disease. It is essential to consider AML in the differential diagnosis when faced with a patient presenting osteolytic lesions and pancytopenia.

Identifying myeloid sarcoma in rare locations is a diagnostic challenge and requires careful evaluation. The optimal management of extramedullary disease requires further investigation, but tissue biopsy and a personalized approach are crucial.

Herein, we describe an unusual case of acute myeloid leukemia presenting with an isolated involvement of the temporal bone after a complete remission of systemic disease for more than a year. The clinical, radiological, and pathological features are discussed, highlighting the importance of considering differential diagnoses and appropriate management.

Myeloid sarcoma (MS) is a rare tumour associated with acute myeloid leukaemia (AML) and occasionally occurs independently. It typically affects skin, bone, lymph nodes, and rarely the gastrointestinal tract, with gastric cases being extremely rare. Notably, no reported instances associate pseudoachalasia with gastric myeloid sarcoma.

A 20-year-old male presented with severe dysphagia, refractory vomiting, and weight loss. Diagnosed with type III achalasia via oesophageal tests, subsequent gastroscopy revealed a large gastric mass, later identified as gastric myeloid sarcoma through histopathology.

MS, characterized by immature blast cells, poses diagnostic challenges without typical leukaemia symptoms. Diagnosis involves immunohistochemistry, employing markers like CD33, CD34, and CD43. Optimal treatments, such as chemotherapy or stem cell transplantation, aim to delay leukaemia progression. Gastric primary de-novo myeloid sarcoma is exceedingly rare, emphasizing the need for tailored treatment strategies.

Gastric myeloid sarcoma is an exceptionally rare tumour, especially without concurrent acute myeloid leukaemia (AML), complicating its diagnosis. This case represents the first globally documented instance of gastric myeloid sarcoma causing pseudoachalasia. Documenting this unique clinical presentation is crucial for a better grasp of gastric myeloid sarcoma's diverse manifestations.

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.

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.

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%).

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.

Myeloid sarcoma is a rare extramedullary haematopoietic malignancy. Interaction between CD47 and signal regulatory protein α (SIRPα) inhibits phagocytosis. CD47-positive tumours confer poor prognoses in various malignant tumours, including acute myeloid leukaemia. This study aimed to investigate the clinicopathological effects of CD47 and SIRPα expression in myeloid sarcoma. Immunohistochemistry (IHC) of CD47 and SIRPα was performed in 84 biopsy samples obtained from patients with myeloid sarcoma, some of which were CD47-positive. Patients were categorised into the following two groups based on IHC of SIRPα: those with SIRPα-positive neoplastic cells (nSIRPα) and, SIRPα expression on non-neoplastic stromal cells in tumour microenvironment (miSIRPα). In addition, patients with CD47 positivity had higher lymphocytic infiltration into the tumour microenvironment. Overall, these patients had significantly higher overall survival, however, no significant difference was observed in progression-free survival. No significant prognostic differences were observed between the nSIRPα and miSIRPα groups. This is the first study to demonstrate an association between CD47 expression and improved prognosis in myeloid sarcoma. Nonetheless, it will be necessary to conduct additional research on gene expression and genomic abnormalities to elucidate the corresponding pathogenesis of myeloid sarcoma.

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.

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.

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.

In this study, we performed a comprehensive molecular analysis of paired skin and peripheral blood/bone marrow (BM) samples from 17 patients with cutaneous myeloid or cutaneous histiocytic-dendritic neoplasms. The cutaneous manifestations included 10 patients with cutaneous acute myeloid leukemia (c-AML), 2 patients with full or partial Langerhans cell differentiation, 2 patients with blastic plasmacytoid dendritic cell neoplasms (BPDCN), 1 patient with both Langerhans cell differentiation and BPDCN, and 2 patients with full or partial indeterminate dendritic cell differentiation. Seven of the 10 c-AML patients (70%) exhibited concurrent or subsequent marrow involvement by acute myeloid leukemia, with all 7 cases (100%) demonstrating shared clonal mutations in both the skin and BM. However, clonal relatedness was documented in one additional case that never had any BM involvement. Nevertheless, NPM1 mutations were identified in 7 of the 10 (70%) of these c-AML cases while one had KMT2A rearrangement and one showed inv(16). All 3 patients (100%) with Langerhans cell neoplasms, 2 patients with BPDCN (100%), and one of the 2 patients (50%) with other cutaneous dendritic cell neoplasms also demonstrated shared mutations between the skin and concurrent or subsequent myeloid neoplasms. Both BM and c-AML shared identical founding drivers, with a predominance of NPM1, DNMT3A, and translocations associated with monocytic differentiation, with common cutaneous-only mutations involving genes in the signal transduction and epigenetic pathways. Cutaneous histiocytic-dendritic neoplasms shared founding drivers in ASXL1, TET2, and/or SRSF2. However, in the Langerhans cell histiocytosis or histiocytic sarcoma cases, there exist recurrent secondary RAS pathway hits, whereas cutaneous BPDCN cases exhibit copy number or structural variants. These results enrich and broaden our understanding of clonally related cutaneous manifestations of myeloid neoplasms and further illuminate the highly diverse spectrum of morphologic and immunophenotypic features they exhibit.

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.

Myeloid sarcoma (MS) is a very rare hematologic disorder. This study analyzes the early treatment options for patients with different types of MS and explores the prognostic factors of MS.

Patients aged 15 years and older with MS in the SEER database (diagnosed from 2000 to 2018) were selected, excluding those with an unknown first course of treatment, an unknown location of disease, and less than 1 month of follow-up. Statistical methods used a chi-square test to compare clinical characteristics; Kaplan-Meier analysis to compare survival differences; and Cox proportional risk models to identify prognostic factors affecting overall survival (OS).

Data were collected from 472 patients: 244 patients with isolated myeloid sarcoma (IMS) and 228 patients with non-isolated myeloid sarcoma (non-IMS). IMS patients mostly chose local treatment, while non-IMS patients mostly chose chemotherapy. There was a significant difference in OS between IMS patients treated with combined treatment and those without treatment. For non-IMS, treated patients had longer OS than untreated, but the difference was not statistically significant. Among adult patients, those younger than 60 years had a better prognosis. Patients with the urinary system, digestive system, reproductive system and chest and abdomen as the initial site had a better prognosis.

Early combination therapy in IMS patients had a longer OS, and chemotherapy combined with radiotherapy/surgery should be the treatment of choice. For non-IMS patients, early combination therapy did not show a significant advantage. Age and location of first presentation were independent factors affecting MS patients' long-term prognosis.

Plasmacytoid dendritic cells (pDCs) are a specific dendritic cell type stemming from the myeloid lineage. Clinically and pathologically, neoplasms associated with pDCs are classified as blastic plasmacytoid dendritic cell neoplasm (BPDCN), mature plasmacytoid dendritic myeloid neoplasm (MPDMN) and pDC expansion in myeloid neoplasms (MNs). BPDCN was considered a rare and aggressive neoplasm in the 2016 World Health Organization (WHO) classification. MPDMN, known as mature pDC-derived neoplasm, is closely related to MNs and was first recognized in the latest 2022 WHO classification, proposing a new concept that acute myeloid leukemia cases could show clonally expanded pDCs (pDC-AML). With the advances in detection techniques, an increasing number of pDC expansion in MNs have been reported, but whether the pathogenesis is similar to that of MPDMN remains unclear. This review focuses on patient characteristics, diagnosis and treatment of pDC expansion in MNs to gain further insight into this novel and unique provisional subtype.

Myeloid sarcoma (MS) is the occurrence of primitive granulocytic precursors in various extramedullary sites. It can occur as an isolated disease, present concomitantly, or during the relapse of various myeloid neoplasms. A high index of clinical suspicion is warranted owing to its varied clinical presentation, rarity of diagnosis, inadequate immunohistochemical techniques, and challenging treatment. The occurrence of myeloid sarcoma of the testis, either as an independent entity or as an initial presentation of acute myeloid leukemia (AML), is exceedingly uncommon, with only a few documented cases in the literature. In this case study, we present a patient who initially presented with testicular swelling, later identified as MS, and subsequently diagnosed as AML through a bone marrow aspirate. This report discusses the diagnostic difficulties encountered and the available therapeutic options for managing MS.

Myeloid sarcoma (MS) is a rare extramedullary parenchymal tumor composed of immature myeloid cells, occurring mainly in the lymph nodes, skin, soft tissue, testicles, bones, peritoneum, and gastrointestinal tract, and rarely in the pancreas. Herein, we report the case of a 68-year-old female patient who visited our hospital for medical assistance due to acute abdominal pain. Abdominal computed tomography (CT) and magnetic resonance imaging showed a mass approximately 8 cm in diameter in the pancreatic tail, which was suspected to be a malignant tumor. To further assess the presence of distant metastases, the patient underwent fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/CT, which revealed an increased 18F-FDG uptake in the corresponding lesions. Subsequently, the patient underwent surgical treatment, and postoperative pathology and immunohistochemistry revealed that the mass was MS. Moreover, we reviewed the clinical features, imaging findings, and histopathology of pathologically confirmed pancreatic MS in the published literature.

We herein report a case of intracranial myeloid sarcoma mimicking hypertensive intracerebral hemorrhage. A 71-year-old man with a history of acute myeloid leukemia was admitted with acute-onset dysarthria. A hematoma-like lesion was found on computed tomography in the left putamen. Magnetic resonance imaging (MRI) and cerebrospinal fluid cytology confirmed the diagnosis of intracranial myeloid sarcoma. The patient showed a favorable response to chemotherapy, and follow-up MRI revealed shrinkage of the tumor. Since the computed tomography findings resemble those of intracerebral hemorrhage, it is important to suspect intracranial neoplasm, particularly in cases with a history of hematologic diseases.

Hematological neoplasms sharing a blastic morphology may involve the skin. The skin may be either the primary site of occurrence of hematological malignancies with blastic features or cutaneous lesions are the first manifestation of an underlying systemic malignancy. The assessment of skin biopsies of hematological neoplasms with blastic features poses diagnostic problems and requires expert hematopathologists considering a wide range of differential diagnoses. The precise diagnosis of diseases sharing blastic features but with different outcomes and requiring distinct therapies is essential for patient management. The present paper mainly focuses on cutaneous involvement of the blastoid variant of mantle cell lymphoma and lymphoblastic lymphoma of B-cell or T-cell origin. The relevant literature has been reviewed and the clinical aspects, pathological features, prognosis, and therapy of both blastoid mantle cell lymphoma and lymphoblastic lymphoma involving the skin are discussed. A focus on other hematological entities with blastic features, which may involve the skin, to be taken into consideration in differential diagnosis is also given.

This is the first case of a promyelocytic sarcoma diagnosed on pleural effusion and exposed the difficulty of demonstrating a leukemic phase in patients with bone diseases, such as Gorham's disease. It also showed that promyelocytic sarcoma can be treated by ATRA/ATO-based therapy with an efficient and tolerated response.

Myeloid sarcoma (MS) is a rare extramedullary tumoral infiltration of immature myeloid cells and can occur in different sites of the body, without leukemic infiltration. A 38-year-old woman patient presented at emergency with a pleural effusion, bicytopenias, and Gorham's disease, a very rare bone disorder. In the following days, she worsened with a chylothorax and pancytopenias. Pleural puncture cytologically revealed promyelocytes with Auer rods. Cytogenetic and molecular analyses subsequently confirmed the presence of the t(15:17) translocation. However, no circulating phase of these atypical promyelocytes was found. Similarly, no other origin was identified. We conclude that the patient had a MS of unknown etiology in the form of a pleural effusion with pathological promyelocytes. The patient was treated with a combination of oral all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) with a cytological and molecular remission persisting 3 months after diagnosis. We report here the first case of a promyelocytic MS of pleural origin without concomitant evidence of acute promyelocytic leukemia. We also show the efficacy of ATRA/ATO treatment in this etiology.