CD30 expression by bone marrow mast cells from different diagnostic variants of systemic mastocytosis

Primary Mast Cell Sarcoma of the Maxillary Sinus and Gingiva Mimicking Malignant Neuroendocrine Tumor: A Case Report

Mast cell sarcoma (MCS) is an extremely rare and aggressive malignancy primarily affecting bones, with limited literature associating it with neuroendocrine marker expression. This report presents a rare case of MCS arising in the maxillary sinus and gingiva. A 74-year-old man presented with a progressively enlarging ulcer on the right-sided upper gingiva. Magnetic resonance imaging revealed a 3.4 cm tumor on the floor of the right maxillary sinus. The patient underwent an inferior maxillectomy and right-sided neck dissection. Microscopically, the tumor consisted of monotonous round cells with oval nuclei, vesicular chromatin, inconspicuous nucleoli, and brisk mitoses. A panel of immunohistochemical stains was initially applied to exclude common sinonasal undifferentiated neoplasms, such as sinonasal undifferentiated carcinoma, melanoma, rhabdomyosarcoma, Ewing sarcoma, and lymphoma. The tumor cells showed patchy staining for INSM1 and synaptophysin, but were negative for AE1/AE3, CAM5.2, p40, chromogranin, S100, HMB45, NKX2.2, desmin, CD45 (LCA), CD3, and CD20, with intact INI1 and BRG1 expression. No specific diagnosis could be rendered based on the staining results, leading to consideration of other rare malignancies. Additional staining revealed positivity for CD117, mast cell tryptase, CD13, CD33, CD43, and CD68, confirming the MCS diagnosis. Molecular testing for KIT mutation was negative. Subsequent bone marrow biopsy demonstrated infiltration of atypical mast cells, which led to a diagnosis of mast cell leukemia. Despite high-dose chemotherapy, the patient died three months after the initial diagnosis. The undifferentiated epithelioid morphology and unusual aberrant neuroendocrine marker expression posed significant diagnostic challenges. The major differential diagnoses were discussed in this report.

Updates in Immunohistochemistry for Hematopoietic and Lymphoid Neoplasms

CONTEXT.—

In their 2014 article "New Immunohistochemistry for B-cell Lymphoma and Hodgkin Lymphoma," Zhang and Aguilera reviewed new immunohistochemical markers for B-cell lymphoma and Hodgkin lymphoma and described how to use these markers for correct lymphoma diagnoses, using the 2008 World Health Organization classifications. Recently, the World Health Organization's WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues published 2022 updates, and, in quick sequence, a second group published an alternative International Consensus Classification of myeloid neoplasms, acute leukemias, and mature lymphoid neoplasms. Regardless of the system a hematopathologist chooses to follow, updates in the immunohistochemical diagnosis of disease are described in both publications as well as in the primary literature. In addition to updated classifications, the increasing use of small biopsy samples for the evaluation of lymphadenopathy continues to challenge hematopathology diagnosis and increase the utilization of immunohistochemistry.

OBJECTIVE.—

To review new immunohistochemical markers or new uses of previously known immunohistochemical markers in the evaluation of hematolymphoid neoplasia for the practicing hematopathologist.

DATA SOURCES.—

Data were obtained from a literature review and personal practice experience.

CONCLUSIONS.—

The practicing hematopathologist requires knowledge of the ever-expanding repertoire of immunohistochemistry for the diagnosis and treatment of hematolymphoid neoplasia. New markers presented in this article help to complete our understanding of disease, diagnosis, and management.

Hematological Neoplasms with Eosinophilia

Eosinophils in peripheral blood account for 0.3-5% of leukocytes, which is equivalent to 0.05-0.5 × 109/L. A count above 0.5 × 109/L is considered to indicate eosinophilia, while a count equal to or above 1.5 × 109/L is defined as hypereosinophilia. In bone marrow aspirate, eosinophilia is considered when eosinophils make up more than 6% of the total nuclear cells. In daily clinical practice, the most common causes of reactive eosinophilia are non-hematologic, whether they are non-neoplastic (allergic diseases, drugs, infections, or immunological diseases) or neoplastic (solid tumors). Eosinophilia that is associated with a hematological malignancy may be reactive or secondary to the production of eosinophilopoietic cytokines, and this is mainly seen in lymphoid neoplasms (Hodgkin lymphoma, mature T-cell neoplasms, lymphocytic variant of hypereosinophilic syndrome, and B-acute lymphoblastic leukemia/lymphoma). Eosinophilia that is associated with a hematological malignancy may also be neoplastic or primary, derived from the malignant clone, usually in myeloid neoplasms or with its origin in stem cells (myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions, acute myeloid leukemia with core binding factor translocations, mastocytosis, myeloproliferative neoplasms, myelodysplastic/myeloproliferative neoplasms, and myelodysplastic neoplasms). There are no concrete data in standardized cytological and cytometric procedures that could predict whether eosinophilia is reactive or clonal. The verification is usually indirect, based on the categorization of the accompanying hematologic malignancy. This review focuses on the broad differential diagnosis of hematological malignancies with eosinophilia.

World Health Organization Classification and Diagnosis of Mastocytosis: Update 2023 and Future Perspectives

Experts of the European Competence Network on Mastocytosis (ECNM) and the American Initiative on Mast Cell Disorders have discussed and updated diagnostic criteria and the classification of mastocytosis, based on new insights in the field and data collected in recent years, mostly within ECNM registry projects in which studies on several thousand cases have been performed. Based on this proposal, the World Health Organization has updated its classification of mastocytosis. This article discusses the revised classification of mastocytosis in light of a rapidly moving field and the advent of new diagnostic parameters, new prognostication tools, and new therapies.

Antibody-Based and Cell Therapies for Advanced Mastocytosis: Established and Novel Concepts

Advanced systemic mastocytosis (SM) is a heterogeneous group of myeloid neoplasms characterized by an uncontrolled expansion of mast cells (MC) in one or more internal organs, SM-induced tissue damage, and poor prognosis. Advanced SM can be categorized into aggressive SM (ASM), MC leukemia (MCL), and SM with an associated hematologic neoplasm (SM-AHN). In a vast majority of all patients, neoplastic cells display a KIT mutation, mostly D816V and rarely other KIT variants. Additional mutations in other target genes, such as SRSF2, ASXL1, or RUNX1, may also be identified, especially when an AHN is present. During the past 10 years, improved treatment approaches have led to a better quality of life and survival in patients with advanced SM. However, despite the availability of novel potent inhibitors of KIT D816V, not all patients enter remission and others relapse, often with a multi-mutated and sometimes KIT D816V-negative disease exhibiting multi-drug resistance. For these patients, (poly)chemotherapy, antibody-based therapies, and allogeneic hematopoietic stem cell transplantation may be viable treatment alternatives. In this article, we discuss treatment options for patients with drug-resistant advanced SM, including novel KIT-targeting drugs, antibody-based drugs, and stem cell-eradicating therapies.

CD30 in Cutaneous Pathology

ABSTRACT

The discovery of CD30 as a diagnostic marker was essential in the identification of not only some lymphomas but also many other solid tumors and benign reactive conditions. Many CD30+ cutaneous disorders and tumors have been categorized since the identification of the marker. With the design of targeted therapies against CD30+ tumoral cells, the interest in CD30 determination was not only diagnostic but also mainly therapeutic. In this article, we explore the historical aspects of the discovery of CD30 and examine the main CD30-related cutaneous pathology, susceptible of anti-CD30 modern treatments.

Systemic mastocytosis in adults: 2023 update on diagnosis, risk stratification and management

OVERVIEW

Systemic mastocytosis (SM) results from clonal proliferation of mast cells (MC) in extracutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal MC clusters in the bone marrow and/or extracutaneous organs. Minor diagnostic criteria include elevated serum tryptase level, MC CD25/CD2/CD30 expression, and presence of activating KIT mutations.

RISK STRATIFICATION

Establishing SM subtype as per the International Consensus Classification/World Health Organization classification systems is an important first step. Patients either have indolent/smoldering SM (ISM/SSM) or advanced SM, including aggressive SM (ASM), SM with associated myeloid neoplasm (SM-AMN), and mast cell leukemia. Identification of poor-risk mutations (i.e., ASXL1, RUNX1, SRSF2, NRAS) further refines the risk stratification. Several risk models are available to help assign prognosis in SM patients.

MANAGEMENT

Treatment goals for ISM patients are primarily directed toward anaphylaxis prevention/symptom control/osteoporosis treatment. Patients with advanced SM frequently need MC cytoreductive therapy to reverse disease-related organ dysfunction. Tyrosine kinase inhibitors (TKI) (midostaurin, avapritinib) have changed the treatment landscape in SM. While deep biochemical, histological and molecular responses have been documented with avapritinib treatment, its efficacy as monotherapy against a multimutated AMN disease component in SM-AMN patients remains unclear. Cladribine continues to have a role for MC debulking, whereas interferon-α has a diminishing role in the TKI era. Treatment of SM-AMN primarily targets the AMN component, particularly if an aggressive disease such as acute leukemia is present. Allogeneic stem cell transplant has a role in such patients. Imatinib has a therapeutic role only in the rare patient with an imatinib-sensitive KIT mutation.

Secretory and Membrane-Associated Biomarkers of Mast Cell Activation and Proliferation

Mast cells (MCs) are immune cells distributed in many organs and tissues and involved in the pathogenesis of allergic and inflammatory diseases as a major source of pro-inflammatory and vasoactive mediators. MC-related disorders are heterogeneous conditions characterized by the proliferation of MC within tissues and/or MC hyper-reactivity that leads to the uncontrolled release of mediators. MC disorders include mastocytosis, a clonal disease characterized by tissue MC proliferation, and MC activation syndromes that can be primary (clonal), secondary (related to allergic disorders), or idiopathic. Diagnosis of MC disorders is difficult because symptoms are transient, unpredictable, and unspecific, and because these conditions mimic many other diseases. Validation of markers of MC activation in vivo will be useful to allow faster diagnosis and better management of MC disorders. Tryptase, being the most specific MC product, is a widely used biomarker of proliferation and activation. Other mediators, such as histamine, cysteinyl leukotrienes, and prostaglandin D2, are unstable molecules and have limitations in their assays. Surface MC markers, detected by flow cytometry, are useful for the identification of neoplastic MC in mastocytosis but, so far, none of them has been validated as a biomarker of MC activation. Further studies are needed to identify useful biomarkers of MC activation in vivo.

The fifth edition of the World Health Organization Classification and the International Consensus Classification of myeloid neoplasms: evolving guidelines in the molecular era with practical implications

PURPOSE OF REVIEW

There have been major advances in our understanding of molecular pathogenesis of myeloid neoplasms, which prompt the updates in the classification of myeloid neoplasms in the fifth edition of World Health Organization Classification (WHO-5) and the new International Consensus Classification (ICC). The purpose of this review is to provide an overview of these two classification systems for myeloid neoplasms.

RECENT FINDINGS

The definition, classification, and diagnostic criteria in many myeloid entities have been refined in WHO-5 and ICC with improved understanding of morphology and integration of new genetic findings. Particularly, molecular and cytogenetic studies have been increasingly incorporated into the classification, risk stratification, and selection of therapy of myeloid neoplasms. Overall, despite some revisions and discrepancies between WHO-5 and ICC, the major categories of myeloid neoplasms remain the same. Further validation studies are warranted to fine-tune and, ideally, integrate these two classifications.

SUMMARY

Integration of clinical information, laboratory parameters, morphologic features, and cytogenetic and molecular studies is essential for the classification of myeloid neoplasms, as recommended by both WHO-5 and ICC.

Proposed European Competence Network on Mastocytosis-American Initiative in Mast Cell Diseases (ECNM-AIM) Response Criteria in Advanced Systemic Mastocytosis

Advanced systemic mastocytosis (AdvSM) is characterized by the presence of KIT D816V and other somatic mutations (eg, in SRSF2, ASXL1, and RUNX1) in 95% and 60% to 70% of patients, respectively. The biological and clinical consequences of AdvSM include multilineage involvement (eg, associated hematologic neoplasm) in 60% to 80% of patients, variable infiltration and damage (C-findings) of predominantly bone marrow and visceral organs through affected mast cell (MC) and non-MC lineages, and elevated levels of serum tryptase. Recently, the treatment landscape has substantially changed with the introduction of the multikinase/KIT inhibitor midostaurin and the selective KIT D816V inhibitor avapritinib. In this review, we discuss the evolution of AdvSM response criteria that have been developed to better capture clinical benefit (eg, improved responses and progression-free and overall survival). We propose refined response criteria from European Competence Network on Mastocytosis and American Initiative in Mast Cell Diseases investigators that use a tiered approach to segregate the effects of histopathologic (eg, bone marrow MC burden, tryptase), molecular (eg, KIT D816V variant allele frequency), clinical (eg, C-findings), and symptom response on long-term outcomes. These response criteria require evaluation in future prospective clinical trials of selective KIT inhibitors and other novel agents.

Standards of Pathology in the Diagnosis of Systemic Mastocytosis: Recommendations of the EU-US Cooperative Group

Pathology plays a central role in the diagnosis of systemic mastocytosis (SM), its delineation from other neoplasms and reactive conditions, and in monitoring of SM under therapy. The morphologic hallmark of SM is the accumulation of spindle-shaped, hypogranulated mast cells (MCs) in bone marrow (BM) and other extracutaneous tissues. Four of the 5 World Health Organization-defined diagnostic criteria (ie, compact MC aggregates [=major criterion]; atypical MC morphology; activating KIT point mutations; aberrant expression of CD25 and/or CD2 and/or CD30 in MCs [=minor criteria]) can be addressed by the pathologist. The final classification of SM variants as either BM mastocytosis, indolent SM, smoldering SM, aggressive SM (ASM), SM with an associated hematologic neoplasm (SM-AHN), or MC leukemia (MCL) has important prognostic significance and requires the integration of certain morphological, clinical, radiological, and biochemical data, referred to as B- and C-findings. Substantial diagnostic challenges may be posed to the pathologist and clinician especially in the so-called advanced SM variants, that is, ASM, MCL, and SM-AHN. In this article, updated recommendations of the EU-US Cooperative Group regarding standards of pathology in the diagnosis of SM, presented during the year 2020 Working Conference held in September in Vienna, are reported.

Systemic Mastocytosis and Other Entities Involving Mast Cells: A Practical Review and Update

Evidence in the recent literature suggests that the presentation spectrum of mast cell neoplasms is broad. In this article, we elaborate on recent data pertaining to minor diagnostic criteria of systemic mastocytosis (SM), including sensitive testing methods for detection of activating mutations in the KIT gene or its variants, and adjusted serum tryptase levels in cases with hereditary α-tryptasemia. We also summarize entities that require differential diagnosis, such as the recently reclassified SM subtype named bone marrow mastocytosis, mast cell leukemia (an SM subtype that can be acute or chronic); the rare morphological variant of all SM subtypes known as well-differentiated systemic mastocytosis; the extremely rare myelomastocytic leukemia and its differentiating features from mast cell leukemia; and mast cell activation syndrome. In addition, we provide a concise clinical update of the latest adjusted risk stratification model incorporating genomic data to define prognosis in SM and new treatments that were approved for advanced SM (midostaurin, avapritinib).

The Expressions of CD30 and CD123 of Mastocytosis in Taiwan

Mastocytosis is a rare disease with a low incidence in Asia-Pacific populations. CD30 and CD123 may have potential prognostic and therapeutic value, but the results are inconsistent. Because racial disparities may exist, we aim to evaluate the expressions of CD30 and CD123 in a series of mastocytosis cases in Taiwan. Twelve patients with systemic and 7 with cutaneous forms of mastocytosis were studied. The expressions of CD30 and CD123 were correlated with the clinical features of the patients. Eighty-three percent (10/12) of patients with systemic mastocytosis (SM) had an associated hematological neoplasm. Four of the SM patients had both "B" and "C" findings, and they had a median survival time of 0.9 months. CD30 expression was positive in 50% (6/12) of SM cases and 100% (6/6) of cutaneous mastocytosis cases. CD123 was expressed focally or weakly in only 2 SM-associated hematological neoplasm cases. The distribution of mastocytosis subtypes and the expression of CD30 and CD123 in Taiwan differed from those reported in North America and Europe. However, mastocytosis, especially indolent forms, is easily overlooked as its heterogeneous and nonspecific clinical manifestations. A high index of suspicion and improved diagnostic methods can be helpful.

Updated Diagnostic Criteria and Classification of Mast Cell Disorders: A Consensus Proposal

Mastocytosis is a hematologic neoplasm characterized by expansion and focal accumulation of neoplastic mast cells (MC) in diverse organs, including the skin, bone marrow (BM), spleen, liver, and gastrointestinal tract. The World Health Organization classification divides the disease into prognostically distinct variants of cutaneous mastocytosis (CM) and systemic mastocytosis (SM). Although this classification remains valid, recent developments in the field and the advent of new diagnostic and prognostic parameters created a need to update and refine definitions and diagnostic criteria in MC neoplasms. In addition, MC activation syndromes (MCAS) and genetic features predisposing to SM and MCAS have been identified. To discuss these developments and refinements in the classification, we organized a Working Conference comprised of experts from Europe and the United States in August 2020. This article reports on outcomes from this conference. Of particular note, we propose adjustments in the classification of CM and SM, refinements in diagnostic criteria of SM variants, including smoldering SM and BM mastocytosis (BMM), and updated criteria for MCAS and other conditions involving MC. CD30 expression in MC now qualifies as a minor SM criterion, and BMM is now defined by SM criteria, absence of skin lesions and absence of B- and C-findings. A basal serum tryptase level exceeding 20 ng/mL remains a minor SM criterion, with recognition that hereditary alpha-tryptasemia and various myeloid neoplasms may also cause elevations in tryptase. Our updated proposal will support diagnostic evaluations and prognostication in daily practice and the conduct of clinical trials in MC disorders.

Systemic Mastocytosis: Multidisciplinary Approach

Systemic mastocytosis (SM) is a heterogeneous group of diseases that affect almost exclusively adults and are defined by the proliferation and accumulation of clonal mast cells (MC) in various tissues. Disease subtypes range from indolent to rare aggressive forms. Although SM is classified as a rare disease, it is believed to be likely underdiagnosed. Major signs and symptoms mainly depend on MC activation and less frequent organ infiltration, typical of more aggressive variants. Diagnosis may be challenging, and symptoms can be aspecific and involve several organs. Therefore, it is advisable to refer patients to specialized centers, having sufficient knowledge of the disease, sensitive diagnostic procedures, offering a personalized and multidisciplinary diagnostic approach, including at least hematological, allergological, dermatological, and rheumatological evaluations. A precise and timely diagnosis is required for: a) adequate counseling of patients and their physicians; b) beginning of symptomatic treatment (anti-mediator therapy); c) prevention of severe manifestations of the disease (i.e., recurrent anaphylaxis, osteoporosis, and bone fractures); d) cytoreductive treatment of advanced SM variants. This review summarizes the disease's main manifestations and describes the ideal diagnostic approach for adult patients with suspected SM, giving physicians the main notions for correct patient diagnosis and management. This review also highlights the importance of a multidisciplinary approach in this very complex disease.

Systemic Mastocytosis: Advances in Diagnosis and Current Management

Mastocytosis is a rare hematologic disorder characterized by abnormal proliferation and accumulation of neoplastic mast cells in various body sites. Isolated skin involvement is termed cutaneous mastocytosis (CM) and the term systemic mastocytosis (SM) refers to multi-organ involvement, most commonly of the bone marrow, skin, liver, and spleen. A subset of patients with SM have an associated clonal hematologic neoplasm which is most commonly myelodysplastic syndrome, chronic myelomonocytic leukemia, or acute myelogenous leukemia and this entity is termed SM with associated hematological neoplasm (AHN). Bone marrow involvement is present in all patients regardless of the subtype of SM. The genetic hallmark of SM is a somatic gain-of-function point mutation within the KIT gene. Other molecular aberrations that have been reported include somatic mutations in TET2, SRSF2, ASXL1, CBL, RUNX1, and RAS and these are common in SM-AHN. The clinical presentation of SM can range from indolent to advanced depending on extent of mast cell burden and genetic profile. In the case of indolent SM, the goal of treatment is to control mediator release-related effects as well as to reduce mast cell burden. In the case of SM-AHN, therapy is primarily that of the AHN and allogeneic hematopoietic stem cell transplantation is the preferred therapy in suitable candidates.

The Role of Avapritinib for the Treatment of Systemic Mastocytosis

Systemic mastocytosis is a rare hematologic disorder characterized by the clonal proliferation of mast cells in extra-cutaneous organs. This disease can be further subdivided into five different phenotypes: indolent systemic mastocytosis (ISM), smoldering systemic mastocytosis (SSM), aggressive systemic mastocytosis (ASM), systemic mastocytosis with an associated hematological neoplasm (SM-AHN) and mast cell leukemia (MCL). The tyrosine kinase inhibitor (and also potent KIT D816V inhibitor) avapritinib, initially approved for the treatment of gastrointestinal stromal tumors (GISTs) bearing a PDGFRA exon 18 mutation, also showed great promise in patients with systemic mastocytosis, a disease known to be driven by a mutation in KIT (D816V). We present an overview of this rare disorder, including a review of the current understanding of the genetic mechanisms which lead to the disease state, the action of the tyrosine kinase inhibitors, as well as the latest clinical trial data which led to the current recommendations for the use of avapritinib.

Developing a standardized approach for assessing mast cells and eosinophils on tissue biopsies: A Work Group Report of the AAAAI Allergic Skin Diseases Committee

Mast cells and eosinophils are commonly found, expectedly or unexpectedly, in human tissue biopsies. Although the clinical significance of their presence, absence, quantity, and quality continues to be investigated in homeostasis and disease, there are currently gaps in knowledge related to what constitutes quantitatively relevant increases in mast cell and eosinophil number in tissue specimens for several clinical conditions. Diagnostically relevant thresholds of mast cell and eosinophil numbers have been proposed and generally accepted by the medical community for a few conditions, such as systemic mastocytosis and eosinophilic esophagitis. However, for other mast cell- and eosinophil-associated disorders, broad discrepancies remain regarding diagnostic thresholds and how samples are processed, routinely and/or specially stained, and interpreted and/or reported by pathologists. These discrepancies can obfuscate or delay a patient's correct diagnosis. Therefore, a work group was assembled to review the literature and develop a standardized consensus for assessing the presence of mast cells and eosinophils for a spectrum of clinical conditions, including systemic mastocytosis and cutaneous mastocytosis, mast cell activation syndrome, eosinophilic esophagitis, eosinophilic gastritis/enteritis, and hypereosinophilia/hypereosinophilic syndrome. The intent of this work group is to build a consensus among pathology, allergy, dermatology, hematology/oncology, and gastroenterology stakeholders for qualitatively and quantitatively assessing mast cells and eosinophils in skin, gastrointestinal, and bone marrow pathologic specimens for the benefit of clinical practice and patients.

Diagnosis of Primary Mast Cell Disorders in Anaphylaxis: Value of KIT D816V in Peripheral Blood

BACKGROUND

Anaphylaxis is frequent in patients suffering from primary mast cell disorders (PMCDs). In patients without mastocytosis in the skin (MIS) and a baseline serum tryptase (bST) less than 30 ng/mL, the diagnosis of PMCD is challenging. In these patients, detection of the KIT D816V mutation in peripheral blood (PB) has been suggested as screening tool for a PMCD.

OBJECTIVE

In this study, we investigated whether KIT D816V in PB can contribute to the decision to perform a bone marrow (BM) biopsy in patients with anaphylaxis without MIS and a bST less than 30 ng/mL.

METHODS

We selected 74 patients with severe anaphylaxis without MIS and a bST less than 30 ng/mL. All underwent a BM biopsy. KIT D816V mutation was quantified in both PB and BM using digital droplet polymerase chain reaction (ddPCR).

RESULTS

Diagnosis of a PMCD was established in 40 patients (54%). Median bST for patients with and without PMCD was, respectively, 9.5 ng/mL (range 4.2-27 ng/mL) and 4.9 ng/mL (range 2.2-20.3 ng/mL) (P <.001). KIT D816V in PB was detected in 16 out of 40 (40%) patients with PMCD. KIT D816V in BM was detected in 22 out of 40 (55%) patients with PMCD.

CONCLUSIONS

In patients without MIS and a bST less than < 30 ng/mL who experience anaphylaxis, determination of KIT D816V mutation in PB is of limited help in deciding when to proceed to a BM biopsy. Therefore, KIT D816V in PB mutation analysis should be interpreted together with scoring tools to make a better assessment in identifying patients who should undergo BM biopsy.

Mast cell differentiation of leukemic blasts in diverse myeloid neoplasms: A potential pre-myelomastocytic leukemia condition

INTRODUCTION

Myeloid neoplasm with blasts showing mast cell (MC)-differentiation and MC-component less than 10% of all nucleated cells but not fulfilling the criteria for systemic mastocytosis with associated hematological neoplasm (SM-AHN) or myelomastocytic leukemia (MML) has not been described in the literature. Herein, we report a study of diverse myeloid malignancies with blasts showing MC-differentiation but not meeting the criteria for SM-AHN or MML. We also evaluated the utility of flow-cytometric immunophenotyping (FCI) in the characterization of immature-MCs (iMCs).

METHODS

We identified nine patients of myeloid neoplasms and studied their morphological, FCI, immunohistochemistry, cytogenetic and molecular characteristics. We also compared the immunophenotypic features of MCs from patient samples with control samples.

RESULTS

The study included patients with newly-diagnosed acute myeloid leukemia (n = 4), chronic myelomonocytic leukemia (n = 1), and chronic myeloid leukemia on follow-up (n = 4) showing MC differentiation in leukemic-blasts. These patients had mildly increased MCs (range, 0.5%-3%) in bone-marrow morphology, including immature-forms and did not meet the criteria for either SM-AHN or MML. On FCI, iMCs were positive for bright-CD117, heterogeneous-CD34, dim-to-negative-HLADR, and moderate-CD203c expression. Expression-levels of CD123 and CD38 were higher (p < 0.001) but CD33 and CD45 were lower in iMCs compared to mature-MC from control samples (p = 0.019 and p = 0.0037).

CONCLUSION

We reported a rare finding of MC differentiation of leukemic blasts in diverse myeloid neoplasms and proposed it as a potential pre-myelomastocytic leukemia condition. We described the distinct immunophenotypic signature of immature-MCs using commonly used markers and highlighted the utility of FCI for the diagnosis of this entity.

Systemic mastocytosis in adults: 2021 Update on diagnosis, risk stratification and management

OVERVIEW

Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MC) in extra-cutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal clusters of spindled MC in the bone marrow. Minor diagnostic criteria include elevated serum tryptase level, abnormal MC CD25 expression, and presence of KITD816V mutation.

RISK STRATIFICATION

Establishing SM subtype as per the World Health Organization classification system is an important first step. Broadly, patients either have indolent/smoldering SM (ISM/SSM) or advanced SM, the latter includes aggressive SM (ASM), SM with associated hematological neoplasm (SM-AHN), and mast cell leukemia (MCL). Identification of poor-risk mutations (ie, ASXL1, RUNX1, SRSF2, NRAS) further refines the risk stratification. Recently, clinical and hybrid clinical-molecular risk models have been developed to more accurately assign prognosis in SM patients.

MANAGEMENT

Treatment goals for ISM patients are primarily directed towards anaphylaxis prevention/symptom control/osteoporosis treatment. Patients with advanced SM frequently need MC cytoreductive therapy to ameliorate disease-related organ dysfunction. High response rates have been seen with small-molecule inhibitors that target mutant-KIT, including midostaurin (Food and Drug Administration approved) or avapritinib (investigational). Other options for MC cytoreduction include cladribine or interferon-α, although head-to-head comparisons are lacking. Treatment of SM-AHN primarily targets the AHN component, particularly if an aggressive disease such as acute myeloid leukemia is present. Allogeneic stem cell transplant can be considered in such patients, or in those with relapsed/refractory advanced SM. Imatinib has a limited therapeutic role in SM; effective cytoreduction is limited to those with imatinib-sensitive KIT mutations.

Case Report: Mastocytosis: The Long Road to Diagnosis

Mastocytosis is a heterogeneous group of disorders characterized by expansion and accumulation of clonal mast cells. Patients mainly present with either cutaneous lesions, anaphylaxis, or both. Its low prevalence and unusual features often hinder its diagnosis for several years. We report the case of an 18-year-old male who was referred to our department with a long-standing history of atypical skin lesions, allergic rhinitis, exercise-induced bronchoconstriction and what was believed to be food-related flushing and anaphylaxis, that was later diagnosed with mastocytosis. This case illustrates the need to consider investigating for mastocytosis when recurrent anaphylaxis is present, especially in the presence of atypical skin lesions, even if normal serum basal tryptase levels and allergic sensitization are present.

A review of CD30 expression in cutaneous neoplasms

BACKGROUND

The surface protein CD30 is a therapeutic target of monoclonal antibody therapy. Knowledge of the frequency of CD30 expression and its prognostic relevance is therefore interesting, not only in lymphoproliferative disorders (LPD) but also in solid tumors of the skin.

METHODS

A review was completed in PubMed for all published reports of CD30 expression in cutaneous lymphomas, mastocytosis, epithelial tumors and sarcomas from 1982 to April 2019. Only accessible articles in English and German were considered. Entities with an expected CD30 expression, such as CD30-positive LPD, were not evaluated.

RESULTS

The electronic research identified 1091 articles and a further 34 articles were obtained from manual bibliographic reference. Overall 91 articles were included that examined CD30 expression in various entities of cutaneous neoplasms and matched the inclusion criteria.

CONCLUSION

Apart from cutaneous CD30-positive LPD, the best-studied group for CD30 expression was mycosis fungoides (MF). CD30 positivity was found in 32% of classical (patch and plaque stage) and in 59.4% cases of transformed MF. CD30 was also frequently expressed in cutaneous mastocytosis (96.5%). In solid tumors, some single reports describe CD30 expression by tumor cells, but CD30-reactive lymphocytes were frequently observed in the tumor microenvironment (TME), especially in keratoacanthoma (KA).

A phase 2 study of brentuximab vedotin in patients with CD30-positive advanced systemic mastocytosis

There is an unmet need for effective therapies for advanced systemic mastocytosis (advSM). CD30 is expressed on the surface of neoplastic mast cells (MC) in more than 50% of patients with advSM. Brentuximab vedotin (BV) is a CD30-directed antibody-drug conjugate with preclinical evidence supporting both an antineoplastic effect and an attenuation of immunoglobulin E-associated mediator release. These observations are the basis for this phase 2 trial of BV monotherapy (1.8 mg/kg IV every 3 weeks up to 8 cycles) in patients with CD30-positive advSM. The primary objective was to determine the efficacy of BV according to International Working Group-Myeloproliferative Neoplasms Research and Treatment-European Competence Network on Mastocytosis (IWG-MRT-ECNM) response criteria. Secondary objectives included evaluation of safety, changes in bone marrow (BM) MC burden, serum tryptase level, flow cytometric quantification of MC surface expression of CD30, and self-reported symptom burden. The trial enrolled 10 patients with a diagnosis of CD30⁺ advSM (aggressive SM, SM with an associated hematologic neoplasm [SM-AHN], or mast cell leukemia [MCL]) with 1 or more signs of SM-related organ damage. According to IWG-MRT-ECNM criteria, none of the patients demonstrated better than stable disease with BV. In addition, there were no significant reductions in BM MC burden, serum tryptase levels, or MC surface expression of CD30. Self-reported symptom scores showed no durable improvement with BV treatment. We conclude that BV is not active as a single agent in CD30⁺ advSM. This trial was registered at www.clinicaltrials.gov as #NCT01807598.

Practical Approaches on CD30 Detection and Reporting in Lymphoma Diagnosis

While our understanding of the biology of CD30 in lymphoma continues to evolve, our need to detect and measure its expression at the protein level remains critically important for diagnosis and patient care. In addition to its diagnostic and prognostic utility, CD30 has emerged as a vehicle for drug targeting through the antibody-drug conjugate brentuximab-vedotin (BV). Given the numerous ways that CD30 is utilized and its emergence as a predictive/prognostic biomarker, pathologists must come to a general consensus on the best reporting structure and methodology to ensure appropriate patient care. In this manuscript, we review the indications for testing, various modalities for testing, technical challenges, pitfalls, and potential standards of reporting. The following questions will try to be addressed in the current review article: What defines a "POSITIVE" level of CD30 expression?; How do we evaluate and report CD30 expression?; What are the caveats in the evaluation of CD30 expression?

The clinical and pathological panoply of systemic mastocytosis

Mastocytosis is a rare disease with varied presentation, myriad symptomatology and variable prognosis. Most patients present with cutaneous disease and mediator-related symptomatology with a small subset having systemic disease (systemic mastocytosis, SM). A subset of the latter develops synchronous or metachronous haematologic neoplasms (SM-AHN), most commonly chronic myelomonocytic leukaemia (CMML). Advanced systemic mastocytosis (ASM) is seen in a relatively small number of patients and is usually associated with organ dysfunction, and may present with hepatosplenomegaly, lymphadenopathy and ascites with progression to leukaemic transformation (mast cell leukaemia/acute myeloid leukaemia) occurring in a few patients. This paper discusses the clinical and pathologic features of the entire spectrum of SM in adults.

The Spectrum of Aggressive Mastocytosis: A Workshop Report and Literature Review

Most cases of mastocytosis are indolent, usually cutaneous mastocytosis or indolent systemic mastocytosis (SM). Aggressive mast cell (MC) diseases are very rare and often fatal. They can develop de novo or due to progression of indolent forms and can present in different ways; either as MC sarcoma or as advanced SM which includes aggressive SM, MC leukemia, and SM with an associated hematological neoplasm. This review will describe these different aggressive forms of mastocytosis, illustrated by cases submitted to the workshop of the 18th Meeting of the European Association for Haematopathology, Basel 2016, organized by the European Bone Marrow Working Group. In addition, the diagnostic criteria for identifying myelomastocytic leukemia, an aggressive myeloid neoplasm with partial MC differentiation that falls short of the criteria for SM, and disease progression in patients with established mastocytosis are discussed.

Immunophenotype of pediatric-onset mastocytosis does not correlate with clinical course

BACKGROUND

Pediatric mastocytosis differs from adult mastocytosis in its presentation and clinical course. However, the data regarding the immunophenotypic characterization of mast cells in children are limited. Our objective was to evaluate the immunophenotype of mast cells in pediatric mastocytosis and correlate it with the clinical course.

METHODS

Biopsy specimens of children with cutaneous mastocytosis were retrieved from the institutions of pathology and were stained for CD25, CD2, and CD30. The percentage of mast cells and the staining intensity were correlated with the clinical data.

RESULTS

Twenty-five biopsy specimens were included in the study. Patients' average age was 15.4 at presentation and 37.5 months at biopsy performance. Clinical presentations included maculopapular cutaneous mastocytosis in 79% and mastocytoma in 21% of cases. CD25, CD2, and CD30 were positive in 60%, 44%, and 84% of the biopsy specimens, respectively. The staining score was significantly higher for CD30 as compared to those for CD25 and CD2 (P = 0.02). No correlation was found between the immunophenotype and the clinical form or course of disease.

CONCLUSIONS

Our results confirm that CD30 is a sensitive marker for pediatric-onset mastocytosis. Nevertheless, its expression does not correlate with clinical subtype or clinical course. The sensitivity of CD25 is higher than that of CD2 in skin lesions.

Relevant updates in systemic mastocytosis

Systemic Mastocytosis (SM) is a rare myeloproliferative neoplasm (MPN) that is characterized by a clonal proliferation of mast cells (MCs). The symptoms and clinical presentation of SM are the result of both MC proliferation as well as activation and degranulation, causing hyperactive and over-exaggerated hypersensitivity responses, as well as organ infiltration by pathogenic MCs. The clinical presentation and course of SM is varied and organ involvement can lead to significant morbidity and mortality in some cases. The subtypes of SM include indolent SM (ISM), smoldering SM (SSM), aggressive SM (ASM), SM with associated hematologic neoplasm (SM-AHN) and mast cell leukemia (MCL) and survival can range from normal in the case of ISM to months in MCL. The treatment of indolent forms of SM is largely focused on addressing symptom burden (B findings), while cytoreductive agents and more recently molecularly targeted agents are employed to reduce MC burden and reverse associated organ dysfunction (C findings). Although the pathogenesis of SM is multi-factorial, the acquisition of KIT D816 V is a relatively frequent mutational event and serves as the target of novel agents. The recent approval of midostaurin for the treatment of advanced SM has brought awareness to this disease and energized further drug development efforts. Expanding our understanding of the underlying molecular mechanisms of SM will continue to inform future therapeutic approaches.

Bone Marrow Mast Cell Antibody-Targetable Cell Surface Protein Expression Profiles in Systemic Mastocytosis

Despite recent therapeutic advances, systemic mastocytosis (SM) remains an incurable disease due to limited complete remission (CR) rates even after novel therapies. To date, no study has evaluated the expression on SM bone marrow mast cells (BMMC) of large panel of cell surface suitable for antibody-targeted therapy. In this study, we analyzed the expression profile of six cell-surface proteins for which antibody-based therapies are available, on BMMC from 166 SM patients vs. 40 controls. Overall, variable patterns of expression for the markers evaluated were observed among SM BMMC. Thus, CD22, CD30, and CD123, while expressed on BMMC from patients within every subtype of SM, showed highly variable patterns with a significant fraction of negative cases among advanced SM (aggressive SM (ASM), ASM with an associated clonal non-MC lineage disease (ASM-AHN) and MC leukemia (MCL)), 36%, 46%, and 39%, respectively. In turn, CD25 and FcεRI were found to be expressed in most cases (89% and 92%) in virtually all BMMC (median: 92% and 95%) from both indolent and advanced SM, but with lower/absent levels in a significant fraction of MC leukemia (MCL) and both in MCL and well-differentiated SM (WDSM) patients, respectively. In contrast, CD33 was the only marker expressed on all BMMC from every SM patient. Thus, CD33 emerges as the best potentially targetable cell-surface membrane marker in SM, particularly in advanced SM.

Mastocytosis: One Word for Different Diseases

Mastocytosis is a neoplastic disease originating from tissue infiltration by transformed mast cells. The diagnosis requires a high grade of suspicion due to the large variety of presenting symptoms. The World Health Organization classification recognizes localized (cutaneous) and systemic forms of the disease, with these forms showing different degrees of aggressiveness. Mastocytosis is often a multiorgan disease, and its correct management requires a multidisciplinary team of experienced consultants to provide overall patient care. Bone marrow evaluation by molecular analyses, skeleton X-ray and abdominal scan together with allergologic and dermatologic evaluation constitute the essential diagnostic work-up for adult patients with mastocytosis. As clinical situations vary, treatment options range from the use of drugs to treat the symptoms, such as anti-H1 receptors and steroids, to UV irradiation, which is overwhelmingly used in patients with cutaneous mastocytosis (CM) or indolent systemic mastocytosis, to cytoreductive treatment to control life-threatening symptoms or organ damage in the more aggressive forms of the disease. Prognosis also widely differs among patients diagnosed with mastocytosis, with the spectrum ranging from an almost normal life expectancy for those with CM and to less than 1-year median overall survival for those with mast cell leukemia.

The new tool "KIT" in advanced systemic mastocytosis

Mastocytosis is a rare disease characterized by KIT-driven expansion and accumulation of neoplastic mast cells in various tissues. Although mediator symptoms related to mast cell activation can impose a symptom burden in cutaneous disease and across the spectrum of systemic mastocytosis subtypes, the presence of an associated hematologic neoplasm and/or organ damage denotes advanced disease and the potential for increased morbidity and mortality. In addition to the revised 2016 World Health Organization classification of mastocytosis, a new diagnostic and treatment toolkit, tethered to enhanced molecular characterization and monitoring, is poised to transform the management of patients with advanced systemic mastocytosis (advSM). Although the efficacy of midostaurin and novel selective KIT D816V inhibitors, such as avapritinib (BLU-285), have validated KIT as a therapeutic target, the clinical and biologic heterogeneity of advSM requires that we reimagine the blueprint for tackling these diseases and use tools that move beyond KIT-centric approaches.

Bone Marrow Expression of Mast Cell Disorders

Mast cell disorders comprise a heterogeneous group of rare diseases, the diagnosis of which still remains a challenge. Bone marrow analysis constitutes the most appropriate site for screening systemic involvement in mastocytosis. Morphologic, immunohistochemical, flow cytometric immunophenotyping, and molecular studies should be routinely performed for diagnostic/prognostic purposes in experienced reference centers during the diagnostic workup in suspected systemic mastocytosis. The authors review the most relevant characteristics of bone marrow expression of mast cell disorders as well as the different methodological approaches to be applied to perform an objective and reproducible diagnosis and classification of mastocytosis and other mast cell disorders.

Prevalence of CD30 immunostaining in neoplastic mast cells: A retrospective immunohistochemical study

Mastocytosis is a rare disease characterized by clonal neoplastic proliferation of mast cells (MCs). It ranges from skin lesions as cutaneous mastocytosis (CM) which may spontaneously regress to highly aggressive neoplasms with multiorgan involvement corresponding to some aggressive systemic mastocytosis (ASM), mast cell leukemia (MCL), and/or mast cell sarcoma (MCS).There is increasing evidence of CD30 expression in neoplastic MCs of the bone marrow. This expression has been described almost exclusively in aggressive forms of systemic mastocytosis (SM).The aim of the present study is to evaluate CD30 expression both in cutaneous and systemic forms of mastocytosis. Forty-two mastocytosis cases were reviewed, including cutaneous (n = 29) and systemic (n = 13) forms to assess the prevalence of CD30 expression. Thirty-nine out of 42 (92.8%) cases were CD30 positive. In cases of CM, 28/29 (96.5%) cases were CD30 positive, 11/13 cases of SM (84.6%) were positive for CD30. MCs in normal skin biopsies and in urticaria lesions were CD30-negative. This study found that CD30 is also frequently expressed in CM as well as in systemic forms. This finding is a major departure from the prevailing concept that CD30 expression is often related to aggressive systemic forms of mastocytosis.

Mast Cell Disease Assessment by Flow Cytometric Analysis

Mast cells are present at a low frequency in bone marrow, rendering high-sensitivity multiparametric flow cytometric analysis an ideal method to assess antigen expression on mast cells. This article discusses the normal antigen expression profile of mast cells, established criteria to identify neoplastic mast cells, and new immunophenotypic markers and approaches to identify the presence of neoplastic mast cells in cases of mastocytosis.

Pathogenesis and Pathology of Mastocytosis

Systemic mastocytosis is a clonal disorder of mast cells that may variably present with characteristic skin lesions, episodes of mast cell mediator release, and disturbances of hematopoiesis. No curative therapy presently exists. Conventional management has relied on agents that antagonize mediators released by mast cells, inhibit mediator secretion, or modulate mast cell proliferation. Recent advances in the molecular understanding of the pathophysiology of systemic mastocytosis have provided new therapeutic considerations, including new and novel tyrosine kinase inhibitors.

Targeted Treatment Options in Mastocytosis

Mastocytosis refers to a heterogeneous group of disorders resulting from the clonal proliferation of abnormal mast cells and their accumulation in the skin (cutaneous mastocytosis when only in the skin, CM) or in various organs (systemic mastocytosis, SM). This leads to a wide variety of clinical manifestations resulting from excessive mediator release in CM and benign forms of SM (indolent SM, ISM) and from tissue mast cell infiltration causing multiorgan dysfunction and failure in more aggressive subtypes (aggressive SM, ASM, or mast cell leukemia). In addition, SM may be associated with hematological neoplasms (AHN). While treatment of ISM primarily aims at symptom management with anti-mediator therapies, cytoreductive and targeted therapies are needed to control the expansion of neoplastic mast cells in advanced forms of SM, in order to improve overall survival. Mast cell accumulation results from a gain-of-function mutation (mostly the D816V mutation) within the KIT tyrosine kinase domain expressed by mast cells and additional genetic and epigenetic mutations may further determine the features of the disease (ASM and AHN). Consequently, tyrosine kinase inhibitors and targeted therapies directed against the oncogenic signaling machinery downstream of KIT are attractive therapeutic approaches. A better understanding of the relative contribution of these genetic and epigenetic events to the molecular pathogenesis of mastocytosis is of particular interest for the development of targeted therapies and therefore to better choose patient subgroups that would best benefit from a given therapeutic strategy.

Activation of TRKA receptor elicits mastocytosis in mice and is involved in the development of resistance to KIT-targeted therapy

The neurotrophins (NTs) play a key role in neuronal survival and maintenance. The TRK (tropomyosin-related kinase) tyrosine kinase receptors (TRKA, TRKB, TRKC) are high affinity receptors for NTs. There is increasing data demonstrating an important role of the TRK family in cancer initiation and progression. NTs have been known for many years to promote chemotaxis, maturation, and survival of mast cells. However, the role of NT signaling in the pathogenesis of mastocytosis is not well understood. In this study, we demonstrate that activation of TRKA by its ligand nerve growth factor (NGF) is potent to trigger a disease in mice with striking similarities to human systemic mastocytosis (SM). Moreover, activation of TRKA by NGF strongly rescues KIT inhibition-induced cell death of mast cell lines and primary mast cells from patients with SM, and this rescue effect can be efficiently blocked by entrectinib (a new pan TRK specific inhibitor). HMC-1 mast cell leukemia cells that are resistant to KIT inhibition induced by TRKA activation show reactivation of MAPK/ERK (extracellular signal-regulated kinase) and strong upregulation of early growth response 3 (EGR3), suggesting an important role of MAPK-EGR3 axis in the development of resistance to KIT inhibition. Targeting both TRK and KIT significantly prolongs survival of mice xenotransplanted with HMC-1 cells compared with targeting KIT alone. Thus, these data strongly suggest that TRKA signaling can improve neoplastic mast cell fitness. This might explain at least in part why treatment with KIT inhibitors alone so far has been disappointing in most published clinical trials for mastocytosis. Our data suggest that targeting both KIT and TRKs might improve efficacy of molecular therapy in SM with KIT mutations.

Advances in the Classification and Treatment of Mastocytosis: Current Status and Outlook toward the Future

Mastocytosis is a term used to denote a heterogeneous group of conditions defined by the expansion and accumulation of clonal (neoplastic) tissue mast cells in various organs. The classification of the World Health Organization (WHO) divides the disease into cutaneous mastocytosis, systemic mastocytosis, and localized mast cell tumors. On the basis of histomorphologic criteria, clinical parameters, and organ involvement, systemic mastocytosis is further divided into indolent systemic mastocytosis and advanced systemic mastocytosis variants, including aggressive systemic mastocytosis and mast cell leukemia. The clinical impact and prognostic value of this classification has been confirmed in numerous studies, and its basic concept remains valid. However, refinements have recently been proposed by the consensus group, the WHO, and the European Competence Network on Mastocytosis. In addition, new treatment options are available for patients with advanced systemic mastocytosis, including allogeneic hematopoietic stem cell transplantation and multikinase inhibitors directed against KIT D816V and other key signaling molecules. Our current article provides an overview of recent advances in the field of mastocytosis, with emphasis on classification, prognostication, and emerging new treatment options in advanced systemic mastocytosis. Cancer Res; 77(6); 1261-70. ©2017 AACR.

Mastocytosis: 2016 updated WHO classification and novel emerging treatment concepts

Over the past few years, substantial advances have been made in understanding the pathogenesis, evolution, and complexity of mast cell neoplasms. New diagnostic and prognostic parameters and novel therapeutic targets with demonstrable clinical impact have been identified. Several of these new markers, molecular targets, and therapeutic approaches have been validated and translated into clinical practice. At the same time, the classification of mastocytosis and related diagnostic criteria have been refined and updated by the consensus group and the World Health Organization (WHO). As a result, more specific therapies tailored toward prognostic subgroups of patients have been developed. Emerging treatment concepts use drugs directed against KIT and other relevant targets in neoplastic mast cells and will hopefully receive recognition by health authorities in the near future. This article provides an overview of recent developments in the field, with emphasis on the updated WHO classification, refined criteria, additional prognostic parameters, and novel therapeutic approaches. Based on these emerging concepts, the prognosis, quality of life, and survival of patients with advanced mastocytosis are expected to improve in the coming years.

Systemic mastocytosis in adults: 2017 update on diagnosis, risk stratification and management

Disease overview:Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MC) in one or more extra-cutaneous organs.

DIAGNOSIS

The major criterion is presence of multifocal clusters of morphologically abnormal MC in the bone marrow. Minor diagnostic criteria include elevated serum tryptase level, abnormal MC expression of CD25 and/or CD2, and presence of KITD816V. Risk stratification: The 2008 World Health Organization (WHO) classification of SM has been shown to be prognostically relevant. Classification of SM patients into indolent (SM), aggressive SM (ASM), SM associated with a clonal non-MC lineage disease (SM-AHNMD) and mast cell leukemia (MCL) subgroups is a useful first step in establishing prognosis.

MANAGEMENT

SM treatment is generally palliative. ISM patients have a normal life expectancy and receive symptom-directed therapy; infrequently, cytoreductive therapy may be indicated for refractory symptoms. ASM patients have disease-related organ dysfunction; interferon-α (±corticosteroids) can control dermatological, hematological, gastrointestinal, skeletal and mediator-release symptoms, but is hampered by poor tolerability. Similarly, cladribine has broad therapeutic activity, with particular utility when rapid MC debulking is indicated; the main toxicity is myelosuppression. Imatinib has a therapeutic role in the presence of an imatinib-sensitive KIT mutation or in KITD816-unmutated patients. Treatment of SM-AHNMD is governed primarily by the non-MC neoplasm; hydroxyurea has modest utility in this setting; there is a role for allogeneic stem cell transplantation in select cases. Investigational drugs: Recent data confirms midostaurin's significant anti-MC activity in patients with advanced SM. Am. J. Hematol. 91:1147-1159, 2016. © 2016 Wiley Periodicals, Inc.

Well-differentiated systemic mastocytosis showed excellent clinical response to imatinib in the absence of known molecular genetic abnormalities: A case report

INTRODUCTION

Well-differentiated systemic mastocytosis (WDSM) is a rare, recently recognized provisional subvariant of systemic mastocytosis (SM). We report a case of WDSM that showed excellent clinical and cutaneous response to imatinib in the absence of known molecular genetic abnormalities.

CLINICAL FINDINGS/DIAGNOSES

We present a 24-year-old woman with childhood onset of skin manifestations that progressed to mediator-related systemic events, and a gastrointestinal tract mastocytoma. A subsequent bone marrow examination showed WDSM. Treatment with imatinib resulted in complete resolution of cutaneous lesions and systemic symptoms, which relapsed with the discontinuation of the drug. Targeted next-generation sequencing-based mutation analysis did not demonstrate any mutations in the coding regions of KIT or other genes commonly associated with myeloid neoplasms.

CONCLUSIONS

The diagnosis of WDSM is challenging in the absence of spindle-shaped mast cells, CD2 or CD25 expression, and KIT D816 mutation. This case illustrated the need for recognizing this unique variant of SM for diagnostic and therapeutic implications.

IL-4 downregulates expression of the target receptor CD30 in neoplastic canine mast cells

CD30 is a novel therapeutic target in human mast cell (MC) neoplasms. In this 'comparative oncology' study, we examined CD30 expression and regulation in neoplastic canine MC using a panel of immunomodulatory cytokines [interleukin-2 (IL-2), IL-4, IL-5, IL-6, IL-13 and stem cell factor (SCF)] and the canine mastocytoma cell lines NI-1 and C2. Of all cytokines tested IL-4 was found to downregulate expression of CD30 in NI-1 and C2 cells. We also found that the CD30-targeting antibody-conjugate brentuximab vedotin induces growth inhibition and apoptosis in both MC lines. Next, we asked whether IL-4-induced downregulation of CD30 interferes with brentuximab vedotin-effects. Indeed, pre-incubation of NI-1 cells with IL-4 decreased responsiveness towards brentuximab vedotin. To overcome IL-4-mediated resistance, we applied drug combinations and found that brentuximab vedotin synergizes with the Kit-targeting drugs masitinib and PKC412 in inhibiting growth of NI-1 and C2 cells. In summary, CD30 is a new marker and IL-4-regulated target in neoplastic canine MC.

Biomarkers of the involvement of mast cells, basophils and eosinophils in asthma and allergic diseases

Biomarkers of disease activity have come into wide use in the study of mechanisms of human disease and in clinical medicine to both diagnose and predict disease course; as well as to monitor response to therapeutic intervention. Here we review biomarkers of the involvement of mast cells, basophils, and eosinophils in human allergic inflammation. Included are surface markers of cell activation as well as specific products of these inflammatory cells that implicate specific cell types in the inflammatory process and are of possible value in clinical research as well as within decisions made in the practice of allergy-immunology.