Mast Cells In Various Tissues Research Articles

Comprehensive Review of Mastocytosis From Pathophysiology to Management Strategies

Introduction: Mastocytosis is a rare hematologic neoplasm characterized by the abnormal proliferation and accumulation of mast cells in various tissues. Its clinical manifestations vary widely, ranging from cutaneous lesions to systemic involvement with potentially life-threatening symptoms. Understanding the pathophysiology, diagnosis, and management of mastocytosis is crucial for improving patient outcomes. 
 
 Aim of the Study: The aim of this study was to provide a comprehensive overview of mastocytosis, including its epidemiology, risk factors, pathophysiology, clinical manifestations, diagnostic approaches, and management strategies. By synthesizing current knowledge on mastocytosis, this study aims to enhance understanding of the disease and guide clinical practice. 
 
 Description of the State of Knowledge: Mastocytosis is classified into cutaneous and systemic forms, with various subtypes based on clinical and histopathological features. Diagnosis relies on a combination of clinical suspicion, serum tryptase levels, histological examination of bone marrow biopsies, and genetic testing. Management strategies include symptomatic treatment, avoidance of triggers, and targeted therapies such as monoclonal antibodies and tyrosine kinase inhibitors. Advanced forms may require cytoreductive therapy or allogeneic hematopoietic stem cell transplantation (alloHSCT). 
 
 Conclusions: Despite advancements in diagnosis and treatment, achieving lasting remission in mastocytosis remains challenging, especially in advanced cases. Further research into the molecular mechanisms underlying the disease and the development of novel therapeutic modalities are needed to improve patient outcomes and quality of life.

Diffuse Cutaneous Mastocytosis: A Current Understanding of a Rare Disease.

Mastocytosis is a heterogeneous disease characterized by the expansion and accumulation of neoplastic mast cells in various tissues. Diffuse cutaneous mastocytosis (DCM) is a rare and most severe form of cutaneous mastocytosis, which typically occurs in childhood. There have been reports of a familial DCM with specific gene mutations, indicating both sporadic and hereditary factors involved in its pathogenesis. DCM is associated with severe MC mediator-related symptoms and an increased risk of anaphylaxis. The diagnosis is based on the appearance of skin lesions, which typically show generalized thickening, erythroderma, blistering dermographism, and a positive Darier's sign. Recognition, particularly in infants, is challenging due to DCMs resemblance to other bullous skin disorders. Therefore, in unclear cases, a skin biopsy is crucial. Treatment focuses on symptom management, mainly including antihistamines and mast cell stabilizers. In extremely severe cases, systemic steroids, tyrosine kinase inhibitors, phototherapy, or omalizumab may be considered. Patients should be equipped with an adrenaline autoinjector. Herein, we conducted a comprehensive review of literature data on DCM since 1962, which could help to better understand both the management and prognosis of DCM, which depends on the severity of skin lesions, intensity of mediator-related symptoms, presence of anaphylaxis, and treatment response.

P30 Blisters in a newborn: all that glitters is not gold

Abstract Mastocytosis is a rare and clinically heterogeneous disease characterized by abnormal accumulation of mast cells in various tissues. There are three major types of cutaneous mastocytosis (CM): diffuse cutaneous mastocytosis (DCM), urticaria pigmentosa and solitary mastocytoma, which is the most common form before the age of 3 months: 90% of CM cases present before 2 years of age, and congenital mastocytosis has been described in 23% of those. Solitary mastocytoma has been associated with a mutation of the KIT gene. A male infant was born at 39 weeks, with a large, indurated, blistering, ulcerated plaque containing yellow serous fluid affecting half his right calf. His nails and oral mucosa were normal. Our centre was contacted on suspected diagnosis of inherited epidermolysis bullosa (EB). There was no family history of EB, and the parents were not related. Initial testing showed a PCR positive for HSV type 1 and treatment with aciclovir and cefotaxime was initiated. There was no improvement after 2 weeks of treatment. Viral and bacterial skin swab were negative. A skin biopsy and ultrasound were performed showing extensive superficial hypoechoic lesion and reactive popliteal lymph nodes and the biopsy confirmed the diagnosis of mastocytoma. Bloods including tryptase level and abdominal ultrasound were normal. The lesion healed within 4 weeks with dressings and topical steroids. This case of a single isolated congenital mastocytoma shows the broad differential diagnoses that must be considered in the evaluation of bullous lesions in a newborn. It is key to biopsy early and always exclude ­infection.

Increased TIM-3 and galectin-9 serum levels in patients with advanced systemic mastocytosis

Systemic mastocytosis is characterized by expansion of clonal mast cells in various tissues. Several biomarkers with diagnostic and therapeutic potential have recently been characterized in mastocytosis, such as the serum marker tryptase and the immune checkpoint molecule PD-L1. We aimed to investigate whether serum levels of other checkpoint molecules are altered in systemic mastocytosis and whether these proteins are expressed in mastocytosis infiltrates in the bone marrow. Levels of different checkpoint molecules were analyzed in serum of patients with different categories of systemic mastocytosis and healthy controls and correlated to disease severity. Bone marrow biopsies from patients with systemic mastocytosis were stained to confirm expression. Serum levels of TIM-3 and galectin-9 were increased in systemic mastocytosis, particularly in advanced subtypes, compared with healthy controls. TIM-3 and galectin-9 levels were also found to correlate with other biomarkers of systemic mastocytosis, such as serum tryptase and KIT D816V variant allele frequency in the peripheral blood. Moreover, we observed expression of TIM-3 and galectin-9 in mastocytosis infiltrates in bone marrow. Together, our results demonstrate for the first time that serum levels of TIM-3 and galectin-9 are increased in advanced systemic mastocytosis. Moreover, TIM-3 and galectin-9 are expressed in bone marrow infiltrates in mastocytosis. These findings provide a rationale for exploring TIM-3 and galectin-9 as diagnostic markers and eventually therapeutic targets in systemic mastocytosis, particularly in advanced forms.

MPN-453 Clinical Presentation and Diagnosis of Advanced Systemic Mastocytosis (AdvSM) in a Community Oncology Setting.

Advanced systemic mastocytosis (AdvSM) is a rare hematologic neoplasm with poor overall survival that is characterized by an accumulation of neoplastic mast cells in various tissues and organs. Although driven by KIT D816V in 95% of cases, the heterogeneous symptom presentation of AdvSM patients may contribute to a lengthy diagnostic journey. To characterize the symptomology of AdvSM patients reported by oncologists at the initial patient encounter in a community-based setting. This was a cross-sectional survey study conducted from August-November 2021. Community oncologists affiliated with Integra Connect were asked to complete a structured eCRF on referral patterns, patient signs and symptoms at initial visit, approach to diagnosis, and ongoing disease management for patients they diagnosed or treated with AdvSM in the prior 24 months. Community oncology practices affiliated with Integra Connect. Twenty-eight community oncologists provided data on 55 AdvSM patients. Twenty-one had managed 2 or more AdvSM patients in the previous 3 years. Mean patient age was 56 years; 55% were female. Comorbid conditions included cardiovascular disease (38%), diabetes (38%), GERD (29%), and COPD/asthma (25%). AdvSM patients were referred to participating oncologists by primary care physicians (33%), immunologists (28%), dermatologists (11%), another oncologist (11%), rheumatologists (7%), and other specialists (9%). 93% of oncologists reported bone marrow biopsy as critical in making an AdvSM diagnosis and indicated that elevated serum tryptase (64%) and detection of KIT D816V (56%) were also important factors in making the AdvSM diagnosis. Cutaneous, gastrointestinal (GI), neuropsychiatric, and musculoskeletal signs and symptoms were common. The most common symptoms reported were pruritis (65%), maculopapular cutaneous mastocytosis (62%), flushing (60%), nausea (58%), and bloating and diarrhea (52%). Allergic reactions (40%), anaphylaxis (24%), dyspnea (35%), anxiety (49%), and fatigue (62%) were also frequently reported at the initial visit. This study shows that AdvSM patients receiving care in a community-based oncology setting are referred to oncologists from a variety of different specialties with a range of disease-related symptoms and multitude of comorbid conditions. Improving awareness of the clinical presentation and diagnostic strategies for AdvSM patients may expedite disease recognition, diagnosis, and treatment initiation.

Covalent heterobivalent inhibitor effectively inhibits anaphylaxis to peanut allergen in a humanized mouse model

Abstract Peanut-induced allergy is an IgE-mediated type I hypersensitivity reaction that manifests symptoms ranging from local edema to life-threatening anaphylaxis. While there are treatments for symptoms in allergic patients resulting from allergen exposure, there are few preventive therapies other than avoidance and no allergen specific therapies. We have previously designed a covalent heterobivalent inhibitor (cHBI) that binds in an allergen-specific manner as a preventive for allergic reactions. Building on previous in vitro testing, in this report we have developed a humanized mouse model to test cHBI efficacy in vivo. Humanized mice (NSG-SCF/GM-CSF/IL-3) developed mature functional human mast cells in various tissues and developed robust anaphylactic reactions when passively sensitized with human IgE monoclonal antibodies specific for peanut allergen. We found that the allergic response is IgE dose-dependent and is mediated by human mast cells indicated by elevated tryptase serum levels and the upregulation of mast cell degranulation markers. Using the validated humanized mouse model, we showed that cHBI inhibited IgE-mediated anaphylaxis and human mast cell degranulation. We demonstrated that cHBI effectively inhibits anaphylaxis for up to 14 days, and cHBI inhibition is specific to peanut allergen. Importantly, cHBI rescued the mice from lethal anaphylactic response during oral peanut-induced anaphylaxis. These findings suggest that cHBI has the potential to be an effective preventative for peanut food allergy in patients.

Cutaneous mastocytosis in childhood.

Mastocytoses are characterized by clonal proliferation of mast cells in various tissues. In childhood, cutaneous mastocytosis (CM) occurs almost exclusively. It is confined to the skin, and has a good prognosis. The most common form is the maculopapular cutaneous mastocytosis (MPCM), formerly called urticaria pigmentosa. A distinction is made between a monomorphic variant of MPCM with multiple small, roundish maculopapular skin lesions and the – more common – polymorphic variant with larger lesions of variable size. One quarter of CM diagnosed in childhood are mastocytomas, which often occur solitary or at multiple sites. The diffuse variant of CM (DCM), which affects 5% of children with CM, should be distinguished from these forms. Systemic mastocytoses (SM) with mast cell infiltrates in the bone marrow or other extracutaneous tissues, such as the gastrointestinal tract, occur predominantly in adults. The diagnosis of CM is usually made clinically: Manifestation in infancy, typical morphology and distribution, pathognomonic Darier sign. Basal serum tryptase is determined if DCM or systemic mastocytosis are to be diagnosed. Children with mastocytosis should be managed in a specialized outpatient clinic. For affected families, detailed information about the clinical picture including prognosis assessment is essential. Mast cell mediated symptoms are controlled by oral non-sedating antihistamines if needed.

Natural evolution in pediatric cutaneous mastocytosis: 10-year follow-up.

Mastocytosis is a heterogeneous group of myeloproliferative disorders characterized by accumulation of clonal mast cells in various tissues. The aim of this study was to determine the symptoms evolution and outcome after 10years observation. Fifty-five children with mastocytosis were included in the study group and monitored concerning mast cell mediator-related symptoms (MC MRSs) and clinical course of the disease for a period of≥10years. Patients presented with a maculopapular cutaneous form of mastocytosis (MPCM) (n=47) and diffuse cutaneous mastocytosis (DCM) (n=8). The complete remission (CR) of skin lesions occurred in 10.3% of children after 10years observation; no remission (NR) was observed in 17.9% children. The CR of skin specific MC MRS occurred in 69.2% children with MPCM and in 14.3% with DCM. Most children with cutaneous mastocytosis (CM) eventually experience a major or partial regression of skin lesions, although complete regression before puberty is rare. The spontaneous remission of skin specific MC MRS is less frequent in children with DCM.

Cutaneous Mastocytosis in a 61-year-old Female from a Dermatological and Histopathological Perspective

First described by Nettleship et al. in 1869 [1], mastocytoses are a heterogeneous group of disorders characterized by the pathologic accumulation of mast cells in various tissues [2-5]. Mastocytosis can be confined to the skin as in cutaneous mastocytosis (CM), or it can involve extracutaneous tissues such as the liver, spleen, bone marrow and lymph nodes, as in systemic mastocytosis [6]. Mastocytosis is a World Health Organization-defined clonal mast cell disorder characterized by significant clinicopathologic heterogeneity [7]. Keywords: Cutaneous mastocytosis; Systemic mastocytosis; Systemic involvement; Mast cells; Mastocytosis.

Recent advances in the understanding and therapeutic management of mastocytosis.

Mastocytosis is a rare disease due to the abnormal accumulation of mast cells in various tissues. Its clinical presentation is heterogeneous depending on mast cell infiltration and mediators release. In some cases, it is associated with hematological malignancies. Prognosis varies from very good with a life expectancy similar to the general population in indolent forms of the disease to a survival time of just a few months in mast cell leukemia. Although in most cases a somatic KIT D816V mutation is found in tumor mast cells, the physiopathology of the disease is not yet fully understood. Additional germline and somatic mutations may explain this heterogeneity. Treatments aim at blocking effect of mast cell mediators, reducing mast cell activation and tumor burden. New drugs mainly directed against the tyrosine kinase activity of KIT have dramatically changed the quality of life and prognosis of mast cell diseases. Present and future therapeutic strategies are discussed in this review.

Deletion of ΔdblGata motif leads to increased predisposition and severity of IgE-mediated food-induced anaphylaxis response.

BackgroundPrevious studies have revealed an important role for the transcription factor GATA-1 in mast cell maturation and degranulation. However, there have been conflicting reports with respect to the requirement of GATA-1 function in mast cell dependent inflammatory processes. Herein, we examine the requirement of GATA-1 signaling in mast cell effector function and IgE-mast cell-dependent anaphylaxis.ObjectiveTo study the requirement of GATA-1 dependent signaling in the development and severity of IgE-mast cell-dependent anaphylaxis in mice.MethodsWild type (Balb/c) and mutant ΔdblGata (Balb/c) mice were employed to study the role of GATA-1 signaling in in vitro IgE-mediated activation of bone marrow derived mast cells (BMMCs). Murine models of passive IgE-mediated and oral antigen-induced IgE-mediated anaphylaxis were employed in mice. Frequency of steady state mast cells in various tissues (duodenum, ear, and tongue), peritoneal cavity, and clinical symptoms (diarrhea, shock, and mast cell activation) and intestinal Type 2 immune cell analysis including CD4+ Th2 cells, type 2 innate lymphoid cells (ILC2), and IL-9 secreting mucosal mast cells (MMC9) were assessedResultsIn vitro analysis revealed that ΔdblGata BMMCs exhibit a reduced maturation rate, decreased expression of FcεRIα, and degranulation capacity when compared to their wildtype (WT) counterparts. These in vitro differences did not impact tissue resident mast cell numbers, total IgE, and susceptibility to or severity of IgE-mediated passive anaphylaxis. Surprisingly, ΔdblGata mice were more susceptible to IgE-mast cell-mediated oral antigen induced anaphylaxis. The increased allergic response was associated with increased Type 2 immunity (antigen-specific IgE, and CD4+ TH2 cells), MMC9 cells and small intestine (SI) mast cell load.ConclusionDiminished GATA-1 activity results in reduced in vitro mast cell FcεRIα expression, proliferation, and degranulation activity. However, in vivo, diminished GATA-1 activity results in normal homeostatic tissue mast cell levels and increased antigen-induced CD4+ Th2 and iMMC9 cell levels and heightened IgE-mast cell mediated reactions.

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.

Preclinical human models and emerging therapeutics for advanced systemic mastocytosis.

Mastocytosis is a term used to denote a group of rare diseases characterized by an abnormal accumulation of neoplastic mast cells in various tissues and organs. In most patients with systemic mastocytosis, the neoplastic cells carry activating mutations in KIT. Progress in mastocytosis research has long been hindered by the lack of suitable in vitro models, such as permanent human mast cell lines. In fact, only a few human mast cell lines are available to date: HMC-1, LAD1/2, LUVA, ROSA and MCPV-1. The HMC-1 and LAD1/2 cell lines were derived from patients with mast cell leukemia. By contrast, the more recently established LUVA, ROSA and MCPV-1 cell lines were derived from CD34+ cells of non-mastocytosis donors. While some of these cell lines (LAD1/2, LUVA, ROSAKIT WT and MCPV-1) do not harbor KIT mutations, HMC-1 and ROSAKIT D816V cells exhibit activating KIT mutations found in mastocytosis and have thus been used to study disease pathogenesis. In addition, these cell lines are increasingly employed to validate new therapeutic targets and to screen for effects of new targeted drugs. Recently, the ROSAKIT D816V subclone has been successfully used to generate a unique in vivo model of advanced mastocytosis by injection into immunocompromised mice. Such a model may allow in vivo validation of data obtained in vitro with targeted drugs directed against mastocytosis. In this review, we discuss the major characteristics of all available human mast cell lines, with particular emphasis on the use of HMC-1 and ROSAKIT D816V cells in preclinical therapeutic research in mastocytosis.

Analytical and clinical validation of an LC–MS/MS method for urine leukotriene E4: A marker of systemic mastocytosis

ObjectivesSystemic mastocytosis (SM) is a disorder characterized by the excessive accumulation of clonally derived mast cells in various tissues. When triggered, mast cells release large amounts of histamine, prostaglandins and leukotrienes. Leukotriene E4 (LTE4) is the primary stable metabolite of total cysteinyl leukotrienes. We hypothesized that secretion of LTE4 would be increased in SM and could be used alone or in combination with current urinary biomarkers to optimize screening for SM. Design and methodsLTE4 was measured by liquid chromatography followed by tandem mass spectrometry (LC–MS/MS). Analytical assay validation was performed using residual urine specimens. LTE4 results were normalized to urine creatinine for clinical use. Reference interval was established using a healthy volunteer cohort. Clinical sensitivity and specificity for SM detection were determined by measuring urinary biomarkers (LTE4, N-methyl histamine [NMH] and 11β-prostaglandin F2α [BPG]) in a cohort of 409 patients referred to allergy specialists, 66 (16%) of which were diagnosed with SM. ResultsUrinary LTE4 measurement was accurate, precise and linear across a range of 31–3020pg/mL. The 95th percentile of the reference interval population was <104pg/mg creatinine. Median urine LTE4 concentrations were significantly higher among patients with SM (97pg/mg cr. vs. 50pg/mg cr.; p<0.01). Elevated urinary LTE4 was 48% sensitive and 84% specific for SM. Clinical sensitivity was 53% for BPG (>1000ng/mL) and 71% for NMH (>200ng/mL). Incorporating all three urinary metabolites improved the SM diagnostic sensitivity to 97%, with minimal change in specificity. ConclusionsWe have developed a sensitive and precise LC–MS/MS assay for quantitation of LTE4 in urine. Incorporating LTE4 into a panel including BPG and NMH provides a much-needed screening tool for a complicated disease with non-specific symptoms and invasive confirmatory testing.

Mastocytosis in the skin in children and adults

Background Mastocytosis is a rare disease of bone marrow-derived hematopoietic progenitor cells, which is characterized by abnormal growth and excessive accumulation of mast cells in various tissues. Cutaneous Mastocytosis is a skin limited disease, whereas Systemic Mastocytosis usually involves bone marrow, spleen, liver, lymph nodes and gastrointestinal tract and may present with or without skin involvement. The skin is one of the most commonly affected organ both in children and adults. Mastocytosis in the skin (MIS) is defined by a typical exanthema and monomorphic mast cell infiltrate. MIS is an initial diagnosis which requires further diagnostic steps leading to the final diagnosis of Cutaneous Mastocytosis or Systemic Mastocytosis.

Mutational Complexity Is Related To Disease Severity In Systemic Mastocytosis

Systemic mastocytosis (SM) is a rare hematologic neoplasm characterized by abnormal accumulation of mast cells in various tissues, predominantly skin, bone marrow and visceral organs. The morphologic phenotype and extent of organ infiltration/dysfunction are basis for the subclassification of SM into indolent SM (ISM), smoldering SM (SSM), SM with associated hematologic non-mast cell disease (SM-AHNMD), aggressive SM (ASM) and mast cell leukemia (MCL). A somatic point mutation in the kinase domain of the receptor tyrosine kinase (TK) KIT at position 816 (KIT D816V) is present in >95% of patients and plays a central role in the pathogenesis and diagnosis of SM. To further explore mechanisms contributing to the clinical diversity of SM, we analyzed 39 KIT D816V mutated patients with different SM subtypes [ISM, n=10; SSM, n=2; ISM-AHNMD, n=5 (CMML, n=2; MDS/MPNu, n=3); ASM, n=1; ASM-AHNMD, n=14 (CMML, n= 5, MDS/MPNu, n=4, HES/CEL, n=2; AML, n=3); MCL, n=3; MCL-AHNMD n=4 (MDS/MPNu, n=2; HES/CEL, n=1; MDS, n=1)] for the presence of additional mutations. We applied next-generation sequencing to investigate ASXL1, CBL, IDH1/2, JAK2, KRAS, MLL-PTD, NPM1, NRAS, TP53, SRSF2, SF3B1, SETBP1, U2AF1 at mutational hotspot regions, and analyzed the complete coding regions of EZH2, ETV6, RUNX1, and TET2. Additional molecular aberrations were identified in 24/27 (89%) patients with advanced SM (SM-AHNMD, 5/5; ASM/MCL, 19/23) while only 3/12 (25%) ISM/SSM patients carried one additional mutation each (U2AF1, SETBP1, CBL) (p<0.001). In TET2, 9 missense, 4 nonsense, 13 frameshift mutations and one in-frame deletion as well as one splice site mutation were found in 15/39 (39%) patients. Ten of 15 (67%) patients carried more than one TET2 mutation. In SRSF2, missense mutations were identified in 14/39 (36%) patients which were clustered at codon 95 (P95H, n=9; P95L, n=2; P95R, n=2), with one additional mutation identified at codon 18 (V18L, n=1). In RUNX1, 10 mutations (9 missense mutations, 1 frameshift) were identified in 9/39 (23%) patients. Ten CBL mutations were identified in 8 patients (8 missense mutations, 1 duplication, 1 splice mutation) and 8 ASXL1 mutations were identified in 8 patients (7 frameshift and 1 nonsense mutation). In 13 patients, two (TET2, n=8; KRAS, n=1), three (CBL, n=2) or four mutations (TET2, n=2) were found in a single gene. Less frequently affected genes were KRAS (n=4), NRAS, JAK2, U2AF1 (n=2, each), EZH2, SETBP1, and ETV6 (n=1, each). No mutations were identified in MLL, IDH1, IDH2, NPM1, SF3B1 and TP53. In advanced SM, 21/27 patients (78%) carried ³3 mutations and 11/27 patients (41%) exhibited ³5 mutations. The median number of mutations was 4. The concurrent presence of KIT-TET2-SRSF2 (10/39, 26%), KIT-SRSF2-RUNX1 (7/39, 18%), KIT-TET2-CBL (5/39, 13%), KIT-SRSF2-ASXL1 (4/39, 10%) and KIT-TET2-ASXL1 (4/39, 10%) was strongly associated with (A)SM/MCL-AHNMD in 16/16 (100%) of patients (CMML, 7/16, 44%; MDS/MPNu, 6/16, 38%; HES/CEL, 3/16, 19%). Clinical follow-up was available for 38 patients. Six of 38 (16%) patients died, all of whom had at least one additional mutation with 5 patients positive for ³3 and 2 patients for ³5 mutations. The median survival of all 26 patients with at least one additional mutation was 12 months. In contrast, none of the 12 cases with KIT D816V mutation only died. This translated into a significant inferior survival (p=0.019) for patients with additional mutations (figure 1). We therefore conclude that, in addition to the multilineage involvement by KIT D816V, the presence of additional molecular aberrations is a new molecular feature that may contribute essentially to the abnormal phenotype and behaviour of neoplastic mast cells in advanced SM and thus to the clinical diversity and prognosis of advanced mast cell disorders. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Non‐allergic, mastocytosis‐associated rhinitis

Systemic mastocytosis (SM) is a clonal proliferative disorder of mast cells (MC) that causes pathological accumulation of mast cells in various tissues, which results in clinical symptoms (e.g. diarrhoea, urticaria) due to MC mediator release. Previous studies have shown that up to fifty percent of rhinitis symptoms in SM patients are non-allergic and it has been assumed that these nasal complaints in SM patients are due an increased nasal mast cell burden. Nevertheless, to date there are no data supporting this hypothesis. The study aims to investigate if the presence of allergy-suggesting nasal complaints in non-allergic SM patients is correlated with objective measure of nasal mast cell burden. Eleven adult patients with systemic mastocytosis underwent a comprehensive rhinologic work-up. All patients fulfilled the clinical ARIA criteria for rhinitis. The allergologic work-up included serological allergy testing, determination of tryptase levels (serum and nasal secretion), skin prick testing, and nasal provocation testing. Ten out of eleven SM patients with clinical persistent allergic rhinitis were found to be non-allergic. In these patients, the most predominant symptoms were rhinorrhea, sneezing, and itching. All three symptoms were strongly correlated with the nasal tryptase level but not to the level of serum tryptase. Non-allergic persistent nasal complaints in systemic mastocytosis were significantly correlated with elevated nasal tryptase level as a measure of local MC burden. Furthermore, elevated nasal tryptase correlated with persistent rhinorrhea, sneezing, and itching as predominant symptoms, which seems to characterize a non-allergic mastocytosis-associated rhinitis (NAMAR) in systemic mastocytosis.

High prevalence of fractures and osteoporosis in patients with indolent systemic mastocytosis

Indolent systemic mastocytosis (ISM) is a rare disease characterized by accumulation of abnormal mast cells in various tissues, including bone marrow. Symptoms are usually related to release of mast cell mediators. The aims are to establish the prevalence of osteoporotic fractures in ISM and to investigate the association with serum tryptase and the urinary histamine metabolites, methylhistamine (MH), and methylimidazole acetic acid. The fracture prevalence in 157 patients (65 men; 92 women), mean age 54 ± 12 years, was assessed by vertebral morphometry and data from patient records, supplemented by a questionnaire. Bone mineral density (BMD) of lumbar spine and femoral neck was measured, and tryptase and histamine metabolites were analysed. We registered 235 lifetime fractures in 154 patients, including 140 osteoporotic (low-energy trauma) fractures, of which 62% were vertebral, 1% hip and 36% other nonvertebral fractures. Osteoporotic fractures and osteoporosis were found in 37% and 28% of the patients, respectively. In men, the prevalence of these osteoporotic manifestations (46% <50 years; 73% ≥50 years) was much higher compared with women (18% <50 years; 58% ≥50 years). Older age, male gender, and higher urinary MH were independently related to the osteoporotic manifestations. This first publication about prevalence of fractures and osteoporosis in patients with ISM shows that the risk of osteoporotic fractures is high, especially in men. Higher urinary MH levels are associated with a higher risk of osteoporotic manifestations. Routine measurements of BMD and vertebral morphometry are warranted in these patients for early detection of osteoporosis.

Mast cells in the intestine and gills of the sea bream, Sparus aurata, exposed to a polychlorinated biphenyl, PCB 126

The presence of mast cells has been reported in all classes of vertebrates, including many teleost fish families. The mast cells of teleosts, both morphologically and functionally, show a close similarity to the mast cells of mammals. Mast cells of teleosts, localized in the vicinity of blood vessels of the intestine, gills and skin, may play an important role in the mechanisms of inflammatory response, because they express a number of functional proteins, including piscidins, which are antimicrobical peptides that act against a broad-spectrum of pathogens. An increase in the number of mast cells in various tissues and organs of teleosts seems to be linked to a wide range of stressful conditions, such as exposure to heavy metals (cadmium, copper, lead and mercury), exposure to herbicides and parasitic infections. This study analyzed the morphological localization and abundance of mast cells in the intestine and gills of sea bream, Sparus aurata, after a 12, 24 or 72h exposure to PCB 126, a polychlorinated biphenyl, which is a potent immunotoxic agent. In the organs of fish exposed to PCB 126, it was observed that in addition to congestion of blood vessels, there was extravasation of red blood cells, infiltration of lymphocytes, and a progressive increase in numbers of mast cells. These data confirm the immunotoxic action of PCB, and the involvement of mast cells in the inflammatory response.

Mastozytose – klinisches Bild

Mastocytosis describes a group of disorders which are characterized by a pathologic increase of mast cells in various tissues. The extent of organ involvement, the severity of clinical symptoms, and the prognosis of patients suffering from mastocytosis may be highly variable. The clinical presentation of mastocytosis ranges from isolated cutaneous disease (cutaneous mastocytosis; CM) to systemic types of mastocytosis (systemic mastocytosis, SM). The latter commonly involves the bone marrow, liver, spleen, lymph nodes and/or the gastrointestinal tract. Symptoms of mastocytosis either result from the activation of mast cells with consecutive release of mediators and/or from the pathologic accumulation of mast cells in various tissues. Skin dysfunction is induced by the local action of mediators, which are released from mast cells upon mechanical or thermal stress. Anaphylactic symptoms may occur in all types of mastocytosis, even in patients with cutaneous involvement only. If anaphylactic reactions occur in patients with mastocytosis, these reactions are most often severe and sometimes even fatal. Diagnostic work-up and treatment of anaphylactic reactions is urgently required. Cutaneous mastocytosis has a good prognosis in children, and often remits several years after the diagnosis has been made. In adults cutaneous mastocytosis with or without systemic mastocytosis is usually persistent. Systemic mastocytosis may occur without significant clinical symptoms (indolent SM; ISM) or may have a major impact on the health of the patients (aggressive SM; ASM). ASM is associated with major medical symptoms, e.g. with osteoporotic fractures especially of the vertebral column or hematologic abnormalities. ISM is without effect on survival time, but life expectancy is significantly shortenend in at least 40% of ASM patients with associate myeloproliferative diseases.