Mastocytosis: the puzzling clinical spectrum and challenging diagnostic aspects of an enigmatic disease

Drug-Induced Anaphylaxis Uncommon in Mastocytosis: Findings From Two Large Cohorts

BACKGROUND

Anaphylaxis is a common feature of patients with mastocytosis, particularly with Hymenoptera venoms. Hence, it is hypothesized that patients with mastocytosis may have an increased susceptibility to developing drug-induced anaphylaxis (DIA). Patients and medical practitioners are therefore concerned when there is a need to use various drugs. However, this issue has not been systematically investigated.

OBJECTIVE

To investigate the prevalence and clinical characteristics of anaphylaxis to various types of drugs among patients with mastocytosis.

METHODS

A retrospective study was conducted among 470 consecutive patients (18 years and older) with confirmed clonal mast cell diseases recruited from 2 independent mastocytosis reference centers. All patients underwent a comprehensive, individualized allergy workup with evaluation of the (self)reported drug hypersensitivity.

RESULTS

The overall prevalence of DIA was 6.3%, accounting for one-third of the confirmed drug hypersensitivity reactions. Nonsteroidal anti-inflammatory drugs were the most common elicitors of DIA (56%), followed by perioperative agents (23%) and antibiotics (13%). Anaphylactic reactions were severe in most cases, with 43% of patients experiencing hypotensive syncope. All drug-related hypersensitivity reactions occurred before mastocytosis was diagnosed.

CONCLUSIONS

The prevalence of DIA in mastocytosis tends to be higher than in the general population, but is overall low. However, its severity is more pronounced. Our results suggest that patients with mastocytosis with a previous reaction to drugs should undergo a thorough allergy workup. Well-tolerated drugs can be further used without specific precautions.

Low Prevalence of Idiopathic Mast Cell Activation Syndrome Among 703 Patients With Suspected Mast Cell Disorders

BACKGROUND

Idiopathic mast cell activation syndrome (iMCAS) is characterized by severe, episodic systemic mast cell (MC) activation and mediator-related symptoms, an event-related increase in serum tryptase levels, and response to MC-targeted therapies in the absence of underlying IgE-mediated allergy or clonal MC disorder. Studies indicating its prevalence using evidence-based diagnostic criteria are lacking.

OBJECTIVE

To assess the prevalence and clinical and laboratory features of patients with iMCAS.

METHODS

We conducted a retrospective evaluation of data from 703 consecutive patients (aged ≥18 years) referred to our center based on suspicion of having MC disorders. Patients underwent a thorough clinical workup including patient history, allergy tests, KIT D816V mutation analysis, and/or bone marrow investigation. Disease activity was prospectively assessed during follow-up visits.

RESULTS

We identified 31 patients with confirmed iMCAS. Furthermore, hereditary α-tryptasemia was detected in three patients with baseline tryptase levels greater than 8 ng/mL. The most common clinical presentation during MCAS episodes was mucocutaneous symptoms in patients with iMCAS, especially urticaria or angioedema. However, these symptoms were less prevalent in patients with clonal MCAS (P = .015). The duration of diagnostic delay was significantly longer in patients with iMCAS compared to those with clonal MCAS (P = .02).

CONCLUSIONS

The overall prevalence of iMCAS was 4.4% in the entire cohort, which indicates that iMCAS is an uncommon condition. To accurately diagnose iMCAS, it is crucial to evaluate suspected patients using the three diagnostic MCAS criteria. This involves performing a comprehensive allergy work-up including laboratory tests and ultrasensitive mutation analysis of KIT D816V. Subsequently, recommended diagnostic algorithms should be applied.

Using the Right Criteria for MCAS

PURPOSE OF REVIEW

The current article aims to provide a comprehensive update on diagnostic criteria for mast cell activation syndrome (MCAS), addressing challenges in diagnosing and classifying MCAS and its variants.

RECENT FINDINGS

In recent years, there has been a significant increase in our knowledge regarding the underlying mechanisms responsible for the activation of mast cells (MCs) in various pathological conditions. Furthermore, a set of criteria and a classification for MCASs have been established. MCAS is characterized by the presence of typical clinical symptoms, a substantial elevation in serum tryptase levels during an attack compared to the patient's baseline tryptase levels, and a response to MC mediator-targeting therapy. In this report, a thorough examination was conducted on the contemporary literature relating to MCAS, with a focus on comparing the specificity, sensitivity, and robustness of MCAS-related parameters within proposals for diagnosing and classifying MCAS and its variants. Moreover, the significance of employing specific consensus criteria in the assessment and categorization of MCAS in individual patients was underscored, due to the escalating occurrence of patients receiving a misdiagnosis of MCAS based on nonspecific criteria.

Diagnostic Significance of Tryptase for Suspected Mast Cell Disorders

Tryptase has proven to be a very useful and specific marker to demonstrate mast cell activation and degranulation when an acute (i.e., within 4 h after the event) and baseline value (i.e., at least 24 h after the event) are compared and meet the consensus formula (i.e., an increase of 20% + 2). The upper limit of normal determined by the manufacturer is 11.4 ng/mL; however, this boundary has been the subject of debate. According to ECNM and AIM experts, the normal range of baseline tryptase should be 1 to 15 ng/mL. A genetic trait, hereditary alpha tryptasemia, characterized by an increased alpha coding TPSAB1 copy number is associated with a baseline value above 8 ng/mL. Elevated tryptase can also be found in chronic kidney disease, obesity, and hematological neoplasms. A tryptase > 20 ng/mL serves as a minor criterion to diagnose systemic mastocytosis and an increase in tryptase > 20% + 2 during an acute event is a required criterion in the diagnosis of mast cell activation syndrome. The goal of this review is to demonstrate the (in)significance of tryptase using some clinical vignettes and to provide a practical guide on how to manage and interpret an elevated tryptase level.

The Diagnostic Workup, Screening, and Treatment Approaches for Patients with Delusional Infestation

Delusional infestation (DI) is a psychiatric disorder defined by the fixed, false belief that one has been infested by an organism without evidence to support this. Patients may present with skin lesions and report abnormal cutaneous sensations. The diagnostic workup for patients presenting with delusional infestation is essential to ensuring accurate diagnosis in ruling out other explanations for symptoms and investigating potential secondary causes of DI. In addition to a comprehensive history and physical examination, laboratory workup should be considered depending on the clinical picture. Antipsychotic medications are the most common drugs used in management of adults with DI and tailor the choice of treatment according to patient characteristics. This article serves as a guide for dermatologists, psychiatrists, and other clinicians as it reviews the workup and screening that should be considered when managing a patient with delusional infestation and subsequent treatment protocols once the diagnosis has been made.

Management of Mediator Symptoms, Allergy, and Anaphylaxis in Mastocytosis

Mastocytosis is characterized by expansion and activation of clonally aberrant mast cells (MCs) in one or more organ systems. Inappropriate MC activation is a key finding in both allergy and mastocytosis; therefore, symptoms in both conditions show some degree of overlap. When mediator release is excessive and involves multiple systems, anaphylaxis may occur. In mastocytosis, the prevalence of atopy is similar to those of the general population, whereas the incidence of anaphylaxis is significantly higher. The purpose of this review is to discuss features of allergy and anaphylaxis as well as the principles of managing MC mediator release symptoms in mastocytosis.

A Puzzling Mast Cell Trilogy: Anaphylaxis, MCAS, and Mastocytosis

Our knowledge of biology and mast cell (MC) function, as well as disorders associated with the pathologic activation of MCs, has evolved over the last few decades. Anaphylaxis, mast cell activation syndrome (MCAS), and mastocytosis are interrelated yet distinct conditions within the spectrum of mast cell activation disorders. Nevertheless, all three conditions can co-exist in one and the same patient, as pathologic MC activation is the key finding in all three. When mediator release is excessive and involves multiple systems, anaphylaxis and MCAS may occur. Furthermore, mastocytosis is a clonal disorder of MCs and often presents with anaphylaxis and MCAS. Nevertheless, in some cases, even the proliferative and accumulative features of MCs in mastocytosis can account for symptoms and disease progression. In each case, diagnosis can be only made when the diagnostic consensus criteria are fulfilled. The current article aims to provide a concise clinical update and pinpoint the main difficulties in diagnosing these puzzling disorders of MCs in medical practice.

Safety and efficacy of lirentelimab in patients with refractory indolent systemic mastocytosis: a first-in-human clinical trial

BACKGROUND

Indolent systemic mastocytosis (ISM) is characterized by excessive mast cell (MC) accumulation and MC-driven signs and symptoms. Currently used therapies are not approved and have limited efficacy. Lirentelimab (AK002) is a monoclonal antibody against sialic acid-binding immunoglobulin-like lectin (Siglec)-8 that inhibits MC activation.

OBJECTIVES

To determine the safety, tolerability and efficacy of lirentelimab in reducing the symptoms of ISM.

METHODS

At a specialty centre for mastocytosis in Germany, we conducted a phase I first-in-human single-ascending and multidose clinical trial of lirentelimab in patients with ISM. Eligible adults had World Health Organization-confirmed ISM and an unsatisfactory response to available treatment. In part A, patients received a single dose of lirentelimab 0.0003, 0.001, 0.003, 0.01 or 0.03 mg kg-1; in part B, patients received one lirentelimab dose of 0.3 mg kg-1 or 1.0 mg kg-1; and in part C, patients received either 1.0 mg kg-1 lirentelimab every 4 weeks for 6 months or ascending doses of lirentelimab (one dose of 1 mg kg-1 followed by five doses of 3-10 mg kg-1 every 4 weeks). The primary endpoint was safety/tolerability. Secondary endpoints included changes from baseline in Mastocytosis Symptom Questionnaire (MSQ), Mastocytosis Activity Score (MAS) and Mastocytosis Quality of Life Questionnaire (MC-QoL) scores at 2 weeks after the final dose.

RESULTS

In 25 patients with ISM (13 in parts A + B and 12 in part C; median age 51 years, 76% female, median 4.6 years from diagnosis), the most common treatment-related adverse events (AEs) were feeling hot (76%) and experiencing a headache (48%). No serious AEs occurred. Median MSQ and MAS symptom severity scores in part C improved (vs. baseline) across all symptoms [MSQ: skin (38-56%), gastrointestinal (49-60%), neurological (47-59%), musculoskeletal (26-27%); MAS: skin (53-59%), gastrointestinal (72-85%), neurological (20-57%), musculoskeletal (25%)]. Median MC-QoL scores improved across all domains: symptoms (39%), social life/functioning (42%), emotions (57%) and skin (44%).

CONCLUSIONS

Lirentelimab was generally well tolerated and improved symptoms and quality of life in patients with ISM. The therapeutic potential of lirentelimab should be considered for ISM.

Mastocytosis and related entities: a practical roadmap

Mastocytosis is a complex heterogenous multisystem disorder that is characterized by pathologic activation or accumulation of neoplastic mast cells (MCs) in one or more organs. This clonal MC expansion is often associated with a somatic gain-of-function mutation (D816V in most of the cases) in the KIT gene, encoding for the MC surface receptor KIT (CD117), a stem cell growth factor receptor. Based on clinical and biochemical criteria, the World Health Organization (WHO) divided mastocytosis into different subclasses. The exact prevalence of mastocytosis remains elusive, but it is estimated that the disease affects approximately 1 in 10,000 persons. The clinical presentation of mastocytosis varies significantly, ranging from asymptomatic patients to a life-threatening disease with multiple organ involvement, potentially leading to cytopenia, malabsorption, hepatosplenomegaly, lymphadenopathy, ascites or osteolytic bone lesions with pathological fractures. Patients with mastocytosis may experience symptoms related to release of MC mediators, such as flushing or diarrhea or even more severe symptoms such as anaphylaxis. Recently, a new genetic trait, hereditary alpha tryptasemia (HaT), was described which involves a copy number variation in the TPSAB1-gene. Its role as standalone multisystem syndrome is heavily debated. There is emerging evidence suggesting there might be a link between HaT and due to the increased prevalence of HaT in patients with SM. The aim of this review is to provide a practical roadmap for diagnosis and management of mastocytosis and its associated entities, since there are still many misconceptions about these topics.Abbreviations: AdvSM: Advanced systemic mastocytosis; ASM: Aggressive systemic mastocytosis; aST: acute serum tryptase; BM: Bone marrow; BMM: Bone marrow mastocytosis; bST: baseline serum tryptase; CM: Cutaneous mastocytosis; DCM: Diffuse cutaneous mastocytosis; HVA: Hymenoptera venom allergy; HaT: Hereditary alpha tryptasemia; ISM: Indolent systemic mastocytosis; MC: Mast cell; MCA: Mast cell activation; MCAS: Mast cell activation syndrome; MCL: Mast cell leukemia; MIS: Mastocytosis in the skin; MMAS: Monoclonal mast cell activation syndrome; MPCM: Maculopapular cutaneous mastocytosis; SM: Systemic mastocytosis; SM-AHN: Systemic mastocytosis with associated hematological neoplasm; SSM: Smouldering systemic mastocytosis; VIT: Venom immunotherapy.

Diagnostic Evaluation of Hypersensitivity Reactions to Antibiotics in a Large Cohort of Mastocytosis Patients

BACKGROUND

Anaphylactic reactions are a well-known feature of mastocytosis, particularly in relation to hymenoptera venom stings. Although data on the frequency of drug hypersensitivity reactions is limited in mastocytosis, it is hypothesized that these patients may be predisposed to hypersensitivity reactions to certain drugs, including antibiotics. Nevertheless, this issue has not been systematically investigated. Thus, we investigate the prevalence and clinical features of hypersensitivity reactions to antibiotics (HRA) in mastocytosis.

METHODS

A 15-year retrospective study was conducted among 239 (≥18 years old) consecutive mastocytosis patients who were investigated in our center. All patients underwent a thorough allergy work-up, where self-reported reactions were individually evaluated by an allergist.

RESULTS

Overall, 34 patients (14.2%) were deemed to have HRA. Most patients reacted with cutaneous symptoms (74%), and anaphylaxis was rare, confirmed only in two of 34 patients (0.8%). Beta-lactams were the most common elicitors (63%). There were no differences in age, gender, atopic status and tryptase levels between mastocytosis patients with and without antibiotic hypersensitivity.

CONCLUSIONS

The present study indicates a similar prevalence of HRA in mastocytosis compared to those of the general population. Moreover, antibiotics appear to be rare elicitors of anaphylaxis in these patients. Hence, our results suggest that mastocytosis patients without a history of HRA may be treated with these drugs without special precautions.

Non-steroidal anti-inflammatory drug-induced anaphylaxis infrequent in 388 patients with mastocytosis: A two-center retrospective cohort study

Background

Anaphylaxis is a well-known feature of mastocytosis, particularly in relation to hymenoptera venom stings. It is therefore hypothesized that mastocytosis patients may also be predisposed to severe hypersensitivity reactions to certain medications including non-steroidal anti-inflammatory drugs (NSAIDs). For this reason, these patients are usually discouraged from using these drugs. The current study aimed to determine the prevalence and evaluate the severity of NSAID-related hypersensitivity reactions among patients with mastocytosis.

Methods

A retrospective study was conducted among a total of 388 (≥18 years old) consecutive patients from two independent European mastocytosis centers, in Sweden and Italy. Patients underwent a thorough allergy work-up where self-reported NSAID-hypersensitivity reactions were re-evaluated by an allergist in the first cohort (202 patients) and results were validated in the second cohort (186 patients).

Results

Overall frequency of NSAID-hypersensitivity was 11.3% in the total study cohort. Most patients reacted with cutaneous symptoms (89%), whereas severe hypersensitivity reactions were infrequent with only 11 patients (2.8%) experiencing anaphylaxis. All NSAID-related hypersensitivity reactions had occurred before mastocytosis was diagnosed. There was no difference between the groups regarding gender, baseline tryptase levels or presence of atopy, asthma/rhinitis.

Conclusion

Our study indicates an approximate 4-fold increased prevalence of NSAID hypersensitivity among mastocytosis patients compared to the general population. However, most NSAID reactions were limited to the skin as the prevalence of overall anaphylaxis was infrequent. Our results support that mastocytosis patients with a known tolerance to NSAIDs can continue using these medications without special precautions, whereas those with a prior reaction to NSAIDs should undergo thorough allergy work-up, including drug challenges.

How persons with systemic mastocytosis describe the time between symptom onset and receiving diagnosis

AIM

The aim of the study was to explore how persons with systemic mastocytosis (SM) described the time between the onset of symptoms and signs and getting the diagnosis.

BACKGROUND

SM is a rare disease caused by the accumulation of clonal mast cells with abnormal function. The symptoms and signs of the disease are varied, often diffuse and affect individuals differently. Due to this complexity, a multi-disciplinary diagnostic approach is required, in which general practitioners play an important part in identifying and referring patients relevant for such investigations.

METHODS

Sixteen persons with SM were interviewed about their experiences of the time before the diagnosis was received. Systematic text condensation was used in the analysis process.

FINDINGS

The time between symptom and signs onset and diagnosis was perceived as difficult. SM often had a complex and unpredictable effect on a person's daily life, long before diagnosis. In the analysis, three themes were found. Having symptoms and signs with an unknown cause included the participants' descriptions of numerous symptoms and signs, often years before diagnosis. These could be severe and result in worries for both participants and their next-of-kin. Dealing with the symptoms and signs encompassed the different ways in which the participants coped with the symptoms and signs, and sought relief. Being a patient without a diagnosis underlined the lack of information and knowledge within healthcare, often resulting in a delayed or incorrect diagnosis. The study highlighted the importance of a person-centred approach and the need to increase knowledge of the disease within primary care, to shorten this stressful and vulnerable time.

Clinical Outcomes of Adults with Systemic Mastocytosis: A 15-Year Multidisciplinary Experience

Systemic mastocytosis (SM) is a rare, clonal, clinically heterogeneous disorder of the mast cells (MCs), and mainly affects adults. The present study aims to describe the clinical and laboratory features as well as the outcomes of SM. A 15-year retrospective study was conducted on 195 consecutive SM patients (aged ≥ 18 years) diagnosed in 2006−2020 at the Multidisciplinary Mastocytosis Center at Karolinska University Hospital. Patients with indolent SM (ISM) represented the most common SM variant (88.2%). Furthermore, the frequencies of aggressive SM and SM with associated non-mast-cell hematological neoplasm were 4.1% and 7.7%, respectively. The prevalence of SM in the adult population of the Stockholm region was estimated to be 10.6/100,000 inhabitants, and the mean incidence of SM cases in the Stockholm region was 0.77/100,000 people per year. In this series, tryptase levels were below 20 ng/mL in 51 patients (26%). Osteoporosis was present in 21.9% of all cases. Interestingly, there was no progression from ISM to advanced SM variants in our study. Furthermore, overall survival was significantly better in ISM patients compared to advanced SM patients (p < 0.0001). Our data suggest that the early recognition and correct diagnosis of SM has prognostic significance.

Perioperative anaphylaxis to fibrin sealants in children with Noonan Syndrome: A retrospective study

BACKGROUND

In the diagnosis of perioperative anaphylaxis, it is essential to define its cause to prevent future reexposures, especially in children with Noonan Syndrome who are characterized by a large number of systemic features and wide-ranging dysmorphia. From an oral surgeon's point of view, apart from an increased risk of tumor incidence, diverse hematologic anomalies are of high concern.

OBJECTIVE

Perioperative management of such patients often requires the use of fibrin sealants, which contain aprotinin. A certain number of anaphylaxis cases have been observed in our daily practice during such treatment, which was the reason for this evaluation.

METHODS

The study was conducted to retrospectively review perioperative anaphylaxis grade II and above in children with Noonan Syndrome who underwent surgeries in the Department of Oral Surgery, Medical University of Lodz, between 2006 and 2021.

RESULTS

Out of the 16 cases of suspected anaphylaxis to aprotinin, 14 were observed in children with Noonan Syndrome. The postoperative serologic screening revealed positive results for qualitative aprotinin-specific immunoglobulin (Ig) G, highly elevated quantitative aprotinin-specific IgG, and slightly elevated aprotinin-specific IgE antibodies. Interestingly, previous aprotinin administration or contact in the past 12 months was excluded.

CONCLUSION

Given that fibrin sealants are typically used in various surgical practices and although the anaphylaxis reactions in such cases are rare, it is essential to be cautious in patients with RASopathies who are at a high risk of developing anaphylaxis.

Safety and efficacy of avapritinib in advanced systemic mastocytosis: the phase 1 EXPLORER trial

Advanced systemic mastocytosis (AdvSM) is a rare hematologic neoplasm driven by the KIT D816V mutation and associated with poor survival. This phase 1 study (NCT02561988) evaluated avapritinib (BLU-285), a selective KIT D816V inhibitor, in patients with AdvSM. The primary endpoints were the maximum tolerated dose, recommended phase 2 dose and safety of avapritinib. Secondary endpoints included overall response rate and changes in measures of mast cell burden. Avapritinib was evaluated at doses of 30–400 mg once daily in 86 patients, 69 with centrally confirmed AdvSM. Maximum tolerated dose was not reached, and 200 mg and 300 mg daily were studied in dose-expansion cohorts. The most frequent adverse events observed were periorbital edema (69%), anemia (55%), diarrhea (45%), thrombocytopenia (44%) and nausea (44%). Intracranial bleeding occurred in 13% overall, but in only 1% of patients without severe thrombocytopenia (platelets <50 × 10⁹/l). In 53 response-evaluable patients, the overall response rate was 75%. The complete remission rate was 36%. Avapritinib elicited ≥50% reductions in marrow mast cells and serum tryptase in 92% and 99% of patients, respectively. Avapritinib induced deep and durable responses, including molecular remission of KIT D816V in patients with AdvSM, and was well tolerated at the recommended phase 2 dose of 200 mg daily.

In a phase 1 trial of patients with advanced systemic mastocytosis, avapritinib, a selective KIT inhibitor, was generally well tolerated, elicited durable clinical responses and led to reductions in mast cell disease burden.

Anaphylaxis and Mast Cell Disorders

There is strong evidence of an association between severe anaphylaxis, especially hymenoptera venom induced, and mast cell (MC) disorders. It has been thought that intrinsic abnormalities in MCs, including the presence of the activating KIT D816V mutation in mastocytosis or of genetic trait, hereditary alpha-tryptasemia, may influence susceptibility to severe anaphylaxis. This article evaluates the potential mechanisms leading to severe MC activation, as well as the differential diagnosis of and range of symptoms attributable to MC mediator release. Also, we offer a global classification for disorders related to MC activation.

Cardiac complications in a patient affected by systemic mastocytosis and primitive myelofibrosis: A case report

Systemic mastocytosis with associated primitive myelofibrosis is a rare and complex disease with a difficult therapeutic management. The release of several inflammation mediators can trigger acute cardiovascular events.

Systemic Mastocytosis: Radiological Point of View

Radiological diagnosis of systemic mastocytosis (SM) can be hard to establish. This difficulty is mainly due to the variable radiological features involving many organ systems (e.g., respiratory, cardiovascular, lympho-reticular, digestive systems, and most commonly skin), and above all, to the broad spectrum of skeletal findings. Skeletal involvement is the most common and prominent imaging feature in patients with SM and represents a prognostic factor as it may entail an aggressive course of the disease. Diagnosis, largely established by histological evaluation of a bone marrow trephine biopsy, supplemented by imaging modalities such as radiography, CT, and magnetic resonance imaging, requires a team approach between the hematologist, radiologist, and pathologist. The general radiologist needs to be familiar with the imaging findings because they may be the first to suggest the correct diagnosis. The primary purpose of this review article was to equip clinicians with pertinent radiological semiotics by presenting relevant radiological features that assist early diagnosis and selection of an effective treatment.

Management of a Lumbar Burst Fracture Occurring After a Sneeze in a Patient Affected by Systemic Mastocytosis: A Case Report

CASE

We present a 36-year-old man with L1 burst fracture after a sneeze. He was in follow-up for indolent systemic mastocytosis (ISM), and osteoporosis was treated with bisphosphonate. Owing to neurologic impairment, posterior decompressive laminectomy and thoraco-lumbar fusion with cemented screws were performed.

CONCLUSION

Vertebral fractures in young patients affected by ISM required a multidisciplinary approach and a careful preoperative planning to achieve acceptable results. These fractures are so rare that even an experienced spine surgeon may not come across them during his whole career. Nevertheless, diagnostic tool improvement makes its diagnosis more frequent, that is why every spine surgeon should know this disease.

Distinct plasma biomarkers confirm the diagnosis of mastocytosis and identify increased risk of anaphylaxis

BACKGROUND

Mastocytosis encompasses a heterogeneous group of disorders characterized by accumulation of clonal mast cells (MCs) in the skin and/or internal organs. Patients typically present with a broad variety of recurrent mediator-related clinical symptoms, including severe anaphylaxis. However, not all patients with mastocytosis experience anaphylactic reactions.

OBJECTIVE

We sought to identify disease-specific biomarkers in plasma that could be used to predict patients with mastocytosis with increased risk of anaphylaxis.

METHODS

Nineteen patients (≥18 years) and 2 control groups (11 subjects with allergic asthma and 13 healthy volunteers without history of atopy) were recruited. In total, 248 plasma proteins were analyzed by Proximity Extension Assay using Olink Proseek Multiplex panels.

RESULTS

We identified 4 novel proteins, in addition to tryptase, E-selectin, adrenomedullin, T-cell immunoglobulin, and mucin domain 1, and CUB domain-containing protein 1/CD138 to be significantly increased in patients with mastocytosis compared with both patients with asthma and healthy controls. Furthermore, we investigated whether we could discriminate between patients with mastocytosis with or without anaphylaxis. In addition to tryptase, we identified 3 novel proteins, that is, allergin-1, pregnancy-associated plasma protein-A, and galectin-3, with significantly different levels in patients with mastocytosis with anaphylaxis compared with those without anaphylaxis.

CONCLUSIONS

Newly identified proteomic biomarkers may be used to predict patients with mastocytosis with increased risk of anaphylaxis.

Idiopathic Anaphylaxis: a Perplexing Diagnostic Challenge for Allergists

PURPOSE OF REVIEW

The aim of this systematic review is to present the proposed theories of pathogenesis for idiopathic anaphylaxis (IA), to discuss its classification, its diagnostic approach, and management.

RECENT FINDINGS

IA represents a major diagnostic challenge and is diagnosed when excluding the possible identifiable triggers of anaphylaxis. The current research, however, revealed that certain conditions including mastocytosis, mast cell activation syndromes, and hereditary alpha tryptasemia can masquerade and overlap with its symptomatology. Also, newly identified galactose-alpha-1,3-galactose mammalian red meat allergy has recently been recognized as underlying cause of anaphylaxis in some cases that were previously considered as IA. IA comprises a heterogenous group of conditions where, in some cases, inherently dysfunctional mast cells play a role in pathogenesis. The standard trigger avoidance strategies are ineffective, and episodes are unpredictable. Therefore, prompt recognition and treatment as well as prophylaxis are critical. The patients should always carry an epinephrine autoinjector.

Bone fragility in patients affected by congenital diseases non skeletal in origin

BACKGROUND

Bone tissue represents a large systemic compartment of the human body, with an active metabolism, that controls mineral deposition and removal, and where several factors may play a role. For these reasons, several non-skeletal diseases may influence bone metabolism. It is of a crucial importance to classify these disorders in order to facilitate diagnosis and clinical management. This article reports a taxonomic classification of non-skeletal rare congenital disorders, which have an impact on bone metabolism METHODS: The International Osteoporosis Foundation (IOF) Skeletal Rare Diseases Working Group (SRD-WG), comprised of basic and clinical scientists, has decided to review the taxonomy of non-skeletal rare disorders that may alter bone physiology.

RESULTS

The taxonomy of non-skeletal rare congenital disorders which impact bone comprises a total of 6 groups of disorders that may influence the activity of bone cells or the characteristics of bone matrix.

CONCLUSIONS

This paper provides the first comprehensive taxonomy of non-skeletal rare congenital disorders with impact on bone physiology.

Low Frequency of IgE-Mediated Food Hypersensitivity in Mastocytosis

BACKGROUND

Patients with mastocytosis have an increased risk for severe anaphylaxis, particularly to Hymenoptera venoms. These patients may also develop more often systemic hypersensitivity reactions to certain foods. However, this issue has not been systematically investigated.

OBJECTIVE

To determine prevalence and severity of food hypersensitivity (FH) reactions among patients with clonal mast cell disorders (CMDs).

METHODS

A retrospective study was conducted among 204 (age ≥18 years) consecutive patients who presented with confirmed CMD (170 with mastocytosis and 34 with monoclonal mast cell activation syndrome). All patients underwent thorough allergy workup where self-reported FH reactions were evaluated.

RESULTS

The prevalence of self-reported FH was 20.6%. The frequency of immunologically mediated reactions was uncommon, because only 3.4% were confirmed by relevant history and IgE sensitization. Among patients with FH, 5 had severe anaphylaxis corresponding to an overall prevalence of 2.5%. Most symptoms were restricted to skin (86%), followed by gastrointestinal tract symptoms (45%)-similar to symptoms that occur in patients with mastocytosis also without food intake. Nuts, spicy foods, seafood, and alcohol were the most common incriminated elicitors. There was no significant difference between the groups regarding age, sex, atopic status, or IgE levels.

CONCLUSIONS

Anaphylaxis from foods in mastocytosis does exist and is severe, although foods are less frequent elicitors than insect venoms. Furthermore, the frequency of overall FH reactions is comparable with that in the general population and most reactions are mild, nonallergic, and unconfirmed. Consequently, our results do not support the elimination of any diet in patients with CMD without a history of FH.

Non-hematologic diagnosis of systemic mastocytosis: Collaboration of radiology and pathology

Systemic mastocytosis (SM) is a hematologic disease with a wide range of clinical courses ranging from an indolent condition with normal life expectancy to exceedingly aggressive disorder with a poor prognosis. The symptoms and signs of SM result from the release of mast cell mediators with heterogeneous functions, and/or organ damage from neoplastic mast cell infiltration, or both. Diagnostic criteria for SM are well-defined by the World Health Organization (WHO). However, the diagnosis of SM can be difficult when especially it is not in the differential diagnosis. Routinely used radiologic techniques (e.g., X-ray, ultrasound, CT scans can show findings such as lytic-, sclerotic- or mixed-bone lesions, splenomegaly, hepatomegaly, retroperitoneal or periportal mesenteric lymphadenopathy, and omental thickening). It is essential to emphasize that the constellation of these radiologic findings should strongly concern of SM, especially in patients who also have a skin rash, allergic reactions, gastrointestinal tract symptoms (lasting, intermittent nausea, diarrhea), paroxysmal tachycardias, unexplained weight loss, persistent bone pain, cytopenias, liver dysfunction, eosinophilia. These findings, even coincidentally noted, will likely lead to a tissue biopsy, which reveals diagnosis (as we discussed and illustrated some tissue biopsies here). Moreover, the role of MRI and new techniques such as [18-fluorodeoxyglucose positron emission computed tomography, fibroscan] in the diagnosis of SM have been discussed. Furthermore, we reviewed the use of radiologic methods to evaluate treatment response and prognostication of SM..

Venom immunotherapy in patients with clonal mast cell disorders: IgG4 correlates with protection

BACKGROUND

Patients with clonal mast cell disorders (cMCD), systemic mastocytosis (SM) and monoclonal mast cell activation syndrome (MMAS), represent an increased risk for Hymenoptera venom anaphylaxis (HVA). Lifelong venom immunotherapy (VIT) is recommended; however, its efficacy and safety are controversial. Hence, we sought to evaluate the efficacy and safety of VIT in HVA patients with cMCD.

METHODS

A retrospective study was conducted among 46 patients with Vespula venom allergy who had experienced severe HVA, 32 cMCD (22 with SM and 10 with MMAS) and 14 controls. There were no differences between cMCD patients and controls in age (58 vs 66) and duration of VIT (47 vs 48 months), respectively.

RESULTS

During VIT, 11 (34%) cMCD patients experienced adverse reactions (ARs) (7% in controls), including 1 anaphylaxis. There were 23 re-stings in 17 (53%) patients during VIT. Of episodes, four (17%) presented with anaphylaxis, 14 (60%) presented with local reaction, and five (23%) were asymptomatic. In 11 episodes (48%), the patient did not take epinephrine, of these 8 (73%) presented with local reaction, and 3 (27%) were asymptomatic. Patient-based protection from anaphylaxis was 76% (4/17) in cMCD vs. 100% in controls during VIT. The venom-specific IgG4 concentrations increased during VIT (P < .001) although tryptase and IgE were unaltered.

CONCLUSION

Both safety and efficacy of VIT in cMCD patients were slightly reduced than controls. Severe ARs were rare. The elevated IgG4 levels may be a biomarker for efficacy of VIT in cMCD patients, as it correlates with protection from re-stings.

Multiple vertebral fractures as the first manifestation of systemic mastocytosis

Systemic mastocytosis is a clonal disease of the mast cell progenitors of the bone marrow. The clinical picture varies from asymptomatic (indolent) to highly aggressive (mast cell leukemia). Up to one-third of patients with SM have osteoporosis and fractures. The following is an analysis of the case of a young patient with multiple fractures as the first manifestation of SM.

Mastocytosis

Mastocytosis is a rare and underdiagnosed disorder characterized by mast cell proliferation in the tissues and organs of the body. The gastrointestinal manifestations of the disease can be noted in approximately 70%-80% of those patients diagnosed with the disorder. Symptomatic manifestations of systemic mastocytosis can either be triggered spontaneously or be precipitated by a variety of situations, stimuli, and exposures. Common gastrointestinal complaints include abdominal pain, diarrhea, nausea, vomiting, and gastrointestinal reflux disease. Substantial numbers of mast cells have been noted in patients who have been diagnosed with gastritis, ulcerative colitis, and Crohn disease. Irreversible, with symptoms that run the gamut from the merely annoying to the severely life-threatening, mastocytosis is a disease that prevents an individual from leading a normal life. As the prevalence of gastrointestinal symptomatology in those patients who have been diagnosed with mastocytosis is so significant, it is an important and relevant disease of which gastroenterology nurses should be cognizant.

Pharmacotherapy of mast cell disorders

PURPOSE OF REVIEW

Mast cell disorders (MCDs) comprise mastocytosis and disorders referred to as mast cell activation syndrome and are caused by abnormal accumulation and/or activation of mast cells in tissues. Clinical signs and symptoms are protean; therefore, finding suitable treatment options for individual patients entails a challenge for clinicians. The purpose of this manuscript is to review the literature on the available therapeutic interventions in patients with MCD.

RECENT FINDINGS

Pharmacotherapy is mainly directed against the effects of mast cells and their mediators. The current recommendations are exclusively based on expert opinions due to the lack of controlled clinical trials. The targeted therapies aiming at blocking mutant KIT variants and/or downstream signaling pathways are currently being developed and may be considered in severely affected, therapy-refractory patients.

SUMMARY

There is currently no method for predicting the best available approach to control symptoms in individual patients with MCD. Therefore, a stepwise, individual-based approach in pharmacotherapy options appears to be most successful strategy and is recommended in all patients. The core component of the treatment in most patients is to control symptoms caused by mast cell mediator release, whereas cytoreductive therapies are mainly reserved for patients with advanced/aggressive systemic mastocytosis.

Review of various molecular targets on mast cells and its relation to obesity: A future perspective

Mast cells are stimulatory factors in prognosis of various immunogenic and allergic diseases in human body. These cells play an important role in various immunological and metabolic diseases. The aim of present article is to explore the molecular targets to suppress the over expression of mast cells in obesity. The last 20 years literature were searched by various bibliographic data bases like Pubmed, google Scholar, Scopus and web of Science. The data were collected by keywords like "Mast Cell" "obesity" and "role of mast cell or role in obesity". Articles and their abstract were reviewed with a counting of 827 publications, in which 87 publications were considered for study and remaining was excluded because of its specificity to the subject. This review explains the characteristics, molecular targets and role of mast cells in obesity and existing research with mast cells to the area of metabolic diseases.

Risk Factor Analysis of Anaphylactic Reactions in Patients With Systemic Mastocytosis

BACKGROUND

Systemic mastocytosis (SM) is a rare disorder of abnormal mast cells in at least 1 extracutaneous organ/tissue. Anaphylaxis is an acute, severe systemic hypersensitivity reaction, and a strong association between SM and anaphylaxis has been shown. However, not all patients with SM experience anaphylaxis. Presently, there are no predictive markers to discriminate patients with SM at high risk of anaphylaxis from those at low risk.

OBJECTIVE

This study sought to determine risk factors for the occurrence of anaphylaxis in patients with SM.

METHODS

A cross-sectional study was conducted in 122 consecutive adult patients with SM admitted to the Mastocytosis Center at Karolinska University Hospital. All patients underwent medical evaluation, including bone marrow biopsy and a thorough allergy workup. To determine risk factors, study subjects were categorized into 2 groups according to the presence (n = 55) or absence (n = 67) of anaphylaxis and compared for their demographic, clinical, and biochemical characteristics.

RESULTS

Patients with SM with anaphylaxis had less frequent presence of mastocytosis in the skin (P < .001), more atopic predisposition (P = .021), higher total IgE levels (P < .001), and lower baseline tryptase levels (27 ng/mL vs 42 ng/mL; P = .024) compared with patients with SM without anaphylaxis.

CONCLUSIONS

Patients with SM with anaphylaxis display unique clinical and laboratory features. Hence, a risk analysis tool that is capable of discriminating patients with SM at high risk of anaphylaxis from those at low risk with 86% sensitivity was developed by using the variables male sex, absence of mastocytosis in the skin, presence of atopy, IgE levels of 15 kU/L or more, and baseline tryptase levels of less than 40 ng/mL.

Mast cell secretome: Soluble and vesicular components

Mast cells are multifunctional master cells implicated in both innate and adaptive immune responses. Their role has been best characterized in allergy and anaphylaxis; however, emerging evidences support their contribution to a wide variety of human diseases. Mast cells, being capable of both degranulation and subsequent recovery, have recently attracted substantial attention as also being rich sources of secreted extracellular vesicles (including exosomes and microvesicles). Along with secreted de novo synthesized soluble molecules and secreted preformed granules, the membrane-enclosed extracellular vesicles represent a previously unexplored part of the mast cell secretome. In this review article we summarize available data regarding the different soluble molecules and membrane-enclosed structures secreted by mast cells. Furthermore, we provide an overview of the release mechanisms including degranulation, piecemeal degranulation, transgranulation, and secretion of different types of extracellular vesicles. Finally, we aim to give a summary of the known biological functions associated with the different mast cell-derived secretion products. The increasingly recognized complexity of mast cell secretome may provide important novel clues to processes by which mast cells contribute to the development of different pathologies and are capable of orchestrating immune responses both in health and disease.

Modeling myeloproliferative neoplasms: From mutations to mouse models and back again

Myeloproliferative neoplasms (MPNs) are defined according to the 2008 World Health Organization (WHO) classification and the recent 2016 revision. Over the years, several genetic lesions have been associated with the development of MPNs, with important consequences for identifying unique biomarkers associated with specific neoplasms and for developing targeted therapies. Defining the genotype-phenotype relationship in MPNs is essential to identify driver somatic mutations that promote MPN development and maintenance in order to develop curative targeted therapies. While studies with human samples can identify putative driver mutations, murine models are mandatory to demonstrate the causative role of mutations and for pre-clinical testing of specific therapeutic interventions. This review focuses on MPN mouse models specifically developed to assess the pathogenetic roles of gene mutations found in human patients, as well as murine MPN-like phenotypes identified in genetically modified mice.