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.

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.

Myeloid Sarcoma of the Breast as Blast Phase of JAK2-Mutated (Val617Phe Exon 14p) Essential Thrombocythemia: A Case Report and a Systematic Literature Review.

INTRODUCTION: Myeloid sarcoma (MS) is a mass-forming proliferation of myeloid blasts. Frequently, it arises as blast phase of pre-existing myeloproliferative, myelodysplastic disorders or consequent to bone marrow transplant. Its molecular characterization has become an increasingly important requirement for the diagnostic definition of this solid leukemia. CASE PRESENTATION: Our case report concerns an MS arising in the breast of a woman with a previous diagnosis of JAK2-mutated essential thrombocythemia (Val617Phe exon 14p) mimicking, on histology, a lobular carcinoma of the breast. The immunohistochemical study of the neoplasm provided the key that solved the diagnostic doubt and the immunohistochemical evaluation of NPM protein expression, which turn out to be negative, provided a clear indication on the molecular status and prognosis of the disease. A year later, the neoplasm relapsed in the pelvic area. DISCUSSION: This diagnostic challenge led us to review the literature of the past 10 years concerning MS of the breast. To the best of our knowledge, this was the first case of MS of the breast occurring in a patient with a history of essential thrombocythemia and recurred in the pelvic region.

Gene Mutations and Targeted Therapies of Myeloid Sarcoma.

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

De novo myeloid sarcoma mimicking gynecological tumors: a retrospective case series of eight patients.

OBJECTIVE: To describe myeloid sarcoma (MS) that mimic gynecological tumors and provide guidelines for improving the diagnosis and treatment of patients. METHODS: This case series study retrospectively analyzed the clinicopathological characteristics and oncological outcomes of female patients who were histologically diagnosed with MS after initially presenting with reproductive-system tumors at the Peking Union Medical College Hospital between January 2000 and March 2022. RESULTS: There were eight cases in which MS mimicked cervical cancer, ovarian cancer, or hysteromyoma. Six patients had isolated MS, and the other two had acute myeloid leukemia (AML)-M2. The average age was 39.00 ± 14.26. They each sought advice from a gynecological oncologist at the initial visit, complaining of irregular bleeding (3/8), low abdominal pain (3/8), dysmenorrhea (1/8), or an accidentally found mass (1/8). CT/MRI exams revealed that the average tumor size reached 5.65 ± 2.35 cm, with 50% of the tumors being larger than 8 cm. The final diagnoses were confirmed by biopsy (2/8) or postoperative pathology (6/8); the most frequent positive immunohistochemical markers were Ki-67 (60-90%), MPO (100%), LCA (62.5%), CD43 (62.5%), CD117 (62.5%), CD99 (50%), vimentin (37.5%), and lysozyme (25%). MLL/AF9 gene fusions and CEBPA, JAK2, NRAS, and FLT3-TKD mutations were found in the patients. Six (75%) of the patients showed a complete response after upfront treatment using chemotherapy + surgery and experienced no recurrence during follow-up. The overall survival (OS) rate was 72.9%, and the 5-year OS rate was 72.9% (95%CI: 0.4056-1.000). The median OS was 26 months (range: 3-82). CONCLUSION: For patients with isolated MS, treatment by chemotherapy and surgery are radical procedure, and initial treatment using chemotherapy alone should be considered for MS with synchronous intramedullary AML. Poor response to chemotherapy, short interval to leukemia occurrence, and heavy tumor burden (> 10 cm) could indicate a poor prognosis for patients with MS.

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.

The changing landscape of pediatric histiocytoses: Birth, life, and transdifferentiation of pediatric histiocytes.

Histiocytic neoplasms in the children are very rare, and histiocytoses can occur in the perinatal period. The presumed origins and presentation of specific histiocytoses in the pediatric age group are described. Common and newly described histiocytoses are presented including Langerhans cell histiocytosis, Rosai-Dorfman disease, histiocytic sarcoma, ALK positive histiocytosis, and hemophagocytic lymphohistiocytosis. Molecular findings common to pediatric histiocytoses are also discussed.

Orbital myeloid sarcoma treated with low-dose venetoclax and a potent cytochrome P450 inhibitor.

CASE REPORT: We report the first case of orbital myeloid sarcoma that was successfully treated with a standard venetoclax dose of 25%. A 38-year-old man with acute myeloid leukemia (AML) post-haplo-hematopoietic stem cell transplantation (HSCT) presented with a nine-month history of progressive right proptosis and a visual acuity deficit. The patient was treated with venetoclax (100 mg orally on days 1-28), cytarabine (40 mg subcutaneously, days 1-10), and itraconazole (100 mg twice daily orally on days 1-28). MANAGEMENT AND OUTCOME: The present case report shows that using cytochrome P450 (CYP) inhibitors is a helpful strategy to reduce the cost of expensive treatments. DISCUSSION: There are limited data on the use of CYP inhibitors as a strategy to reduce the costs of expensive drugs (i.e. venetoclax). This approach has some advantages over standard dose venetoclax (400 mg/day) such as significantly reduced costs (which is relevant for patients in low-income countries). In this case, we used itraconazole-a potent CYP3A4 inhibitor-which can theoretically reduce the dose to 100 mg/day without losing serum therapeutic concentrations.

Intracranial myeloid sarcoma as the first presentation of acute myeloid leukemia and literature review.

INTRODUCTION: Intracranial myeloid sarcoma is a rare extramedullary presentation of acute myeloid leukemia (AML). It can involve the meninges and ependyma presenting as extra-axial mass lesion. Rarely, it can also invade the brain parenchyma. It is commonly seen in children. It is usually misdiagnosed due to its close resemblance to other intracranial tumors (meningioma, metastasis, Ewing's sarcomas, and lymphoma). These are underdiagnosed if they precede the diagnosis of leukemia. CASE REPORT: A 7-year-old boy with isolated intracranial myeloid sarcoma who presented with raised intracranial pressure (ICP) which was successfully managed by surgical excision. CONCLUSION: Isolated intracranial myeloid sarcoma is a rare presentation of AML. Leukemia can be diagnosed early during the postoperative period and can be started on therapy timely. These patients requires regular follow-ups (clinical, laboratory and radiological) to detect relapses early.

Myeloid sarcoma in a newborn: A rare manifestation of congenital acute myeloid leukemia.

Cutaneous myeloid sarcoma is rarely present prior to the diagnosis of congenital acute myeloid leukemia (AML); the former is typically diagnosed with or after the leukemia. We report a 2-day-old male born with multiple cutaneous red to violaceous nodules. Histopathologic and immunohistochemistry findings from a skin nodule were suspicious for myeloid sarcoma. Bone marrow biopsy was initially negative for aberrant blasts; however, at age 4 months, AML with a KMT2A gene rearrangement was identified via bone marrow biopsy.

Isolated intracranial myeloid sarcoma: report of a case and review of the literature.

Myeloid sarcoma is a rare malignant tumor of primitive myeloid cell origin often associated with hematologic disorders. The central nervous system is rarely involved and differentiating between myeloid sarcoma and other tumors is not possible on imaging. Here we present the rare case of an isolated intracranial myeloid sarcoma, initially misdiagnosed radiologically as a meningioma, treated with surgical total resection and subsequent chemotherapy, with no signs of any hematological disorder at follow up. Differential diagnosis and management strategies, as well as follow-up implications are discussed along with literature review, which pointed out that only five cases with no further signs of hematological disorders at follow up have been described in the literature so far and this case has the longest follow up of them at 9 years.

Molecular annotation of extramedullary acute myeloid leukemia identifies high prevalence of targetable mutations.

BACKGROUND: Genomic landscape of extramedullary acute myeloid leukemia (EM-AML), including myeloid sarcoma (MS) and leukemia cutis (LC), is not well characterized. The potential utility of next-generation sequencing (NGS) using EM tissue is not established. METHODS: In this multicenter retrospective study, clinical and NGS data were collected on patients with EM-AML. All statistical analyses were performed in SPSS Statistics (v 26). RESULTS: Our study included 58 patients with EM-AML. The median age at diagnosis was 62 years; 59% of patients had MS and 33% had LC. EM-AML was isolated (i.e., without blood or marrow involvement) in 31% and was first noted at relapse in 60% of patients. Median overall survival in our cohort was 18.2 months overall, with 19.1 months and 11.6 months in the newly diagnosed and the relapsed/refractory patients, respectively. At least one targetable or potentially targetable alteration was present in 52% of patients with EM-site NGS, with 26% IDH1, 21% NPM1, 11% IDH2, 6% FLT3, and 13% KMT2A-PTD. Mutations in IDH1 were significantly more prevalent on NGS from EM tissue than non-EM (blood or marrow) samples (26% vs. 3%; p = .030). Three of four patients treated with IDH inhibitors based on EM-site NGS experienced a complete response. CONCLUSIONS: Targetable mutations are frequent in EM-AML and EM-site NGS is warranted for selecting potential targeted therapies for patients with EM-AML.

Identification of RCC1-LCK as a novel fusion gene in pediatric erythroid sarcoma.

Erythroid sarcoma is a very rare subtype of myeloid sarcoma with undetermined biological features. Here, we present an infant with a multifocal erythroid sarcoma, diagnosed because the tumor cells were positive for glycophorin A. After acute myeloid leukemia-oriented chemotherapy and surgical resection followed by cord blood transplantation, he has successfully maintained complete remission without any late effects. Total transcriptome analysis of the tumor identified a novel fusion gene, RCC1-LCK, and high LCK expression levels, suggesting that LCK overexpression was involved in leukemogenesis in this case.

Gilteritinib in Isolated Breast Relapse of FLT3 Positive Acute Myeloid Leukemia: A Case Report and Review of Literature.

Extramedullary relapse of acute myeloid leukemia (AML) is not a rare event, and the FMS-like tyrosine kinase 3 (FLT3) mutation is a well-known risk factor. Gilteritinib is approved for relapsed/refractory FLT3+ AML, but its efficacy in extramedullary relapse is still undefined. Here, we present the case of a 69-year-old woman with therapy-related nucleophosmin-1 and FLT3-internal tandem duplication (FLT3-ITD) positive AML treated with induction and consolidation with CPX-351 (liposomal daunorubicin plus cytarabine) followed by off-label azacitidine maintenance who obtained a complete remission (CR) with persistent measurable residual disease. After 19 months of CR, she experienced an isolated breast relapse of FLT3-ITD+ AML. She was started on single-agent gilteritinib, resulting in a rapid and persistent complete regression of the breast nodule. Targeted therapy with gilteritinib for relapsed/refractory FLT3-ITD+ AML can be effective in isolated extramedullary relapse.

Unusual presentations of central nervous system myeloid sarcoma.

Myeloid sarcoma (MS), also termed 'chloroma' or 'granulocytic sarcoma', is a tumour mass consisting of myeloid blasts occurring at an anatomical site other than the bone marrow. MS occurs in up to 8% of patients with acute myeloid leukaemia. While MS typically involves the skin or lymph nodes, almost any tissue can be affected, and symptoms largely depend on the organ involved and subsequent mass effect. We present a case series of patients that presented to a tertiary hospital with MS affecting the central nervous system over a 4-month period. These three cases demonstrate the vast spectrum of clinical presentations of MS and, furthermore, show rare examples of intramedullary spinal cord involvement and disseminated intraparenchymal brain disease.

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.

[Successful treatment of myelodysplastic syndromes complicated by myeloid sarcoma with haploidentical allogeneic hematopoietic stem cell transplantation using post-transplant cyclophosphamide].

Using post-transplant cyclophosphamide (PTCy-haplo), haploidentical allogeneic hematopoietic stem cell transplantation has shown a surge in popularity in recent years. There are, however, only a few reports of PTCy-haplo being used to treat myelodysplastic syndromes (MDS) that have been complicated by myeloid sarcoma (MS). An immuno-suppressive therapy was given to a 25-year-old man who was diagnosed with low-risk MDS in September 2007. After an ileocecal ulcer biopsy that revealed MS in July 2019, a chromosomal analysis of the bone marrow cells in August 2019 revealed loss of chromosome 7, which is associated with poor prognosis. Because the patient lacked an HLA-matched sibling donor, he underwent PTCy-haplo in December 2019. On day 33, complete remission and donor chimerism was achieved. Ileocecal ulcer scarring was discovered by a colonoscopy on day 54. Grade I cutaneous acute graft-versus-host disease was discovered approximately on day 30 and treated with topical steroids. PTCy-haplo may be an effective treatment for MS.

[Myeloid sarcomas of the shoulder and testis relapsing 9 years after allogenic stem cell transplantation for acute myeloid leukemia].

This report describes a 56-year-old man who was diagnosed with myeloid sarcoma (MS) of the testis and right shoulder after receiving allogenic stem cell transplantation (allo-SCT) at the age of 47 for acute myeloid leukemia (AML) with inv (16) (p13.1;q22). Nine years after allo-SCT, he complained of a painful right testicular mass. He underwent orchiectomy, and the pathologic diagnosis was MS. Inv (16) was identified by fluorescence in situ hybridization (FISH) using testicular tumor specimens. 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) revealed FDG accumulation in the right shoulder. FISH analysis of bone marrow aspirate revealed no increase in blasts and ruled out CBFB-MYH11 fusion. Reinduction chemotherapy, consolidation, and local radiation therapy for the left testis and right shoulder were administered to him. After that, he received a second allo-SCT from an unrelated donor who was HLA-matched. As of 2 years after the second allo-SCT, recurrence of neither AML nor myeloid sarcoma has been observed. The recurrence of MSs without bone marrow involvement is frequently reported in single, multiple single organs, or multiple single regions. Even if MSs recur in a distant location, combining systemic and local treatment may be a better treatment strategy.

[Radiotherapy for the treatment of leukemia]. / Strahlentherapeutische Behandlung von Leukämien.

Background: Lymphoma cells are highly radiosensitive and consequently, radiation therapy is a rational addition to systemic therapy in the treatment of leukemia. Especially as a conditioning regimen before allogeneic stem cell transplantation, radiation therapy, in the form of total body irradiation, is an established concept. Objectives: The present work provides an overview on the execution and side effects of radiation treatment in leukemia. Especially (long-term) side effects after total body irradiation are presented. Materials and methods: A selective search in the database PubMed on radiation treatment of leukemia and on total body irradiation has been carried out, focusing on toxicities as well as technical and conceptional innovations. Results: Total body irradiation is a successful conditioning therapy before allogeneic stem cell transplantation and is accompanied by a diverse, but manageable, toxicity spectrum with endocrinological, cardiopulmonary, ophthalmological, nephrological and neurological long-term side effects as well as secondary neoplasia. In addition, low-dose radiotherapy may be utilized to treat myeloid sarcoma (chloroma). Conclusions: The variety of side effects after total body irradiation requires an interdisciplinary and long-term aftercare provided by radiation oncologists and medical oncologists/the transplantation team. Technical evolutions may result in a more selective targeting of the bone marrow and lymphatic organs. At the moment, these techniques are not established in clinical routine but are being evaluated in clinical trials.

Redistribution, homing and organ-invasion of neoplastic stem cells in myeloid neoplasms.

The development of a myeloid neoplasm is a step-wise process that originates from leukemic stem cells (LSC) and includes pre-leukemic stages, overt leukemia and a drug-resistant terminal phase. Organ-invasion may occur in any stage, but is usually associated with advanced disease and a poor prognosis. Sometimes, extra-medullary organ invasion shows a metastasis-like or even sarcoma-like destructive growth of neoplastic cells in local tissue sites. Examples are myeloid sarcoma, mast cell sarcoma and localized blast phase of chronic myeloid leukemia. So far, little is known about mechanisms underlying re-distribution and extramedullary dissemination of LSC in myeloid neoplasms. In this article, we discuss mechanisms through which LSC can mobilize out of the bone marrow niche, can transmigrate from the blood stream into extramedullary organs, can invade local tissue sites and can potentially create or support the formation of local stem cell niches. In addition, we discuss strategies to interfere with LSC expansion and organ invasion by targeted drug therapies.