The presence of mast cell clonality in patients with unexplained anaphylaxis

Mastocytosis

Mastocytosis is a spectrum of clonal myeloid disorders defined by abnormal growth and accumulation of mast cells in various organ systems. The disease is divided into cutaneous mastocytosis, systemic mastocytosis (SM) and mast cell sarcoma. SM is further categorized into several non-advanced and advanced forms. The prognosis of cutaneous mastocytosis and non-advanced SM is mostly favourable, whereas prognosis and survival in advanced SM and mast cell sarcoma are poor. During the past 15 years, major advances have been made in the diagnosis, prognosis and management of patients with mast cell neoplasms. Management of mastocytosis consists of symptomatic therapy, including anti-mast cell mediator drugs, and cytoreductive agents for patients with advanced disease and selected individuals with non-advanced disease, as well as recognition and prevention of comorbidities such as osteoporosis and anaphylaxis. The preclinical and clinical development of KIT-D816V-targeting drugs, such as midostaurin or avapritinib, mark a milestone in improving management, the quality of life and survival in patients with SM. These agents induce major responses or even remission in people with advanced SM and lead to rapid improvement of mediator-related symptoms and quality of life in symptomatic patients.

Test Panel of Hidden Allergens for "Idiopathic Anaphylaxis" Reveals Wheat Allergy Dependent on Augmentation Factors as Common Final Diagnosis

BACKGROUND

Idiopathic anaphylaxis (IA) is an unresolved concern. Hidden allergens may be relevant in IA and in nonsteroidal anti-inflammatory drug hypersensitivity (NSAID-HS).

OBJECTIVE

To identify hidden elicitors for IA and NSAID-HS by a skin prick test (SPT) (13 allergens) and allergen-specific IgE (sIgE) panel (12 allergens) and to determine the value of each tested allergen.

METHODS

We retrospectively included all patients from 2018 to 2021 referred with a suspicion of IA or NSAID-HS by history in whom SPT and/or sIgE to allergens of the IA panel were performed. Patient characteristics from patients' records included comorbidities, history and symptoms of anaphylaxis, serum baseline tryptase level, total IgE level, SPT, sIgE, challenge results, and final diagnoses.

RESULTS

A total of 134 patients (77 female, mean age 39.7 ± 14.6 years) were included. Median serum baseline tryptase and total IgE levels were 4.23 μg/L and 133.5 kU/L, respectively. Allergologic workup with the IA panel resulted in positive SPT and sIgE in 61 (47%) and 66 (60%) patients, respectively. In those, confirmation or exclusion of allergy, mostly by challenge, led to a definitive diagnosis in 61 of 134 patients (46%). Skin prick test was most frequently positive to gluten (22.4%) and sIgE to ω5-gliadin (21.6%), which correlated with the history (r = 0.310, P < .001; and r = 0.407, P < .001, respectively). In 28 of 134 patients (21%) with initially suspected IA or NSAID-HS, challenges confirmed occult food allergy in which wheat allergy dependent on augmentation factors was the most frequent cause of anaphylaxis (19%).

CONCLUSIONS

Wheat allergy dependent on augmentation factors should be considered in all patients with anaphylaxis of unknown cause or after NSAID intake.

Mast cell activation syndrome: An up-to-date review of literature

Mast cells are a subtype of white blood cells and are involved in the immune system. These cells contain many chemical substances called mediators, which are involved in the allergic response. The fact that mast cells play a role in many events that require urgent intervention, especially anaphylaxis, has led to a more detailed study of these cells. The diseases also caused by dysfunctions of mast cells have been examined in many circumstances. For instance, mast cell activation syndrome is known as an augmented number of cells due to decreased cell death, resulting in clinical symptoms affecting many systems. The main common symptoms include flushing, hypotension, urticaria, angioedema, headache, vomiting and diarrhea. Although the underlying mechanism is not yet clearly known, we aim to review the literature in a broad perspective and bring together the existing knowledge in the light of the literature due to the diversity of its involvement in the body and the fact that it is a little known syndrome.

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.

Predictors of Clonality and Underlying Mastocytosis in Mast Cell Activation Syndromes

PURPOSE OF REVIEW

Mast cell (MC) activation can present with a wide range of symptoms. The mechanisms that cause such activation are varied. One of them is the presence of clonal MCs which is defined, within other possible changes, by the presence of a somatic, activating mutation in the KIT gene. The clinical course and prognosis of patients with this underlying disease may be different from other causes of MC activation (MCA). For this reason, it is important to early diagnose, or at least suspect, which patients with MCA are due to clonal MCs.

RECENT FINDINGS

The diagnosis of clonality must be made in a comprehensive manner. However, this paper reviews chronologically each of the stages from the patient's first visit to the doctor's office which can be indicative of clonality: clinical presentation of MCA, physical examination, analytical determinations of tryptase, and/or KIT mutational analysis and bone involvement, among others. The different clonality predictive scores proposed are also reviewed and compared. Although the gold standard for the diagnosis of certainty of MC clonality is the performance of a bone marrow (BM) biopsy, there are clinical symptoms, signs, and biological parameters suggestive of clonality, as well as predictive scores, which can guide (or rule out) an early diagnosis and avoid unnecessary BM biopsies.

Anaphylaxis: A 2023 practice parameter update

This practice parameter update focuses on 7 areas in which there are new evidence and new recommendations. Diagnostic criteria for anaphylaxis have been revised, and patterns of anaphylaxis are defined. Measurement of serum tryptase is important for diagnosis of anaphylaxis and to identify underlying mast cell disorders. In infants and toddlers, age-specific symptoms may differ from older children and adults, patient age is not correlated with reaction severity, and anaphylaxis is unlikely to be the initial reaction to an allergen on first exposure. Different community settings for anaphylaxis require specific measures for prevention and treatment of anaphylaxis. Optimal prescribing and use of epinephrine autoinjector devices require specific counseling and training of patients and caregivers, including when and how to administer the epinephrine autoinjector and whether and when to call 911. If epinephrine is used promptly, immediate activation of emergency medical services may not be required if the patient experiences a prompt, complete, and durable response. For most medical indications, the risk of stopping or changing beta-blocker or angiotensin-converting enzyme inhibitor medication may exceed the risk of more severe anaphylaxis if the medication is continued, especially in patients with insect sting anaphylaxis. Evaluation for mastocytosis, including a bone marrow biopsy, should be considered for adult patients with severe insect sting anaphylaxis or recurrent idiopathic anaphylaxis. After perioperative anaphylaxis, repeat anesthesia may proceed in the context of shared decision-making and based on the history and results of diagnostic evaluation with skin tests or in vitro tests when available, and supervised challenge when necessary.

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.

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.

Disease Spectrum of Anaphylaxis Disorders

Anaphylaxis results from massive mast cell activation. Mechanisms of mast cell activation may involve IgE- and non-IgE-mediated triggers, clonal mast cell disease, or be idiopathic and may be modified by several factors including but not restricted to hormonal status, stress, heritable factors, mast cell burden, and simultaneous exposure to more than 1 factor. Patients with recurrent anaphylaxis with a nonidentifiable trigger present a particular challenge in diagnosis and management. Presence of clonal disease may be suggested by hypotensive episodes with urticaria and angioedema, and high baseline tryptase levels. A number of scoring systems have been developed to identify patients who are at high risk to have underlying mastocytosis. This review provides an overview of anaphylaxis disorders and our current understanding of their mechanisms of action, evaluation, and management.

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.

Hidden and Rare Food Allergens in Pediatric Age

In food allergy management, the avoidance of the allergen that caused the reaction plays a fundamental role. Nevertheless, that can be thwarted in case of accidental exposure to a rare or hidden allergen, causing the adoption of a monotonous diet and a consequent reduction in the quality of life of the patient and their family. The identification of a rare and hidden allergen is an important diagnostic challenge, taking into account that a significant proportion of all food reactions is in reality due to them. The aim of the present review is to provide the pediatric allergist an overview of the possible sources of rare and hidden food allergens, taking into consideration the routes of exposure to these potential allergens with the main examples published in the scientific literature and the distinction between types of direct or cross-contamination. The identification of the allergen responsible for the reaction and the provision of a dietary advice customized for the specific individual's dietary habits is essential to improve quality of life of the familiar nucleus and to reduce the risk of further allergic reactions.

Mast Cell Activation Syndromes: Comparison Between Two Scoring Models to Predict for Mast Cell Clonality

BACKGROUND

The Red Española de Mastocitosis (Spanish Network on Mastocytosis) score (REMAs) and the National Institutes of Health idiopathic clonal anaphylaxis score (NICAS) were developed for more efficient screening of mast cell (MC) clonality in MC activation syndromes. In a limited idiopathic anaphylaxis case series, the NICAS showed higher accuracy compared with the REMAs.

OBJECTIVE

To compare the performance of the REMAs against the NICAS in the diagnosis of MC clonality.

METHODS

We compared the diagnostic value of the REMAs against the NICAS in 182 patients (63% men, median age 56 years) who presented with anaphylaxis triggered by Hymenoptera venom allergy (45%), drugs (15%), food (11%), idiopathic anaphylaxis (20%), and mixed causes (10%). KIT mutation was assessed in parallel in whole blood and bone marrow (BM) and, when negative, in highly purified BM MC. TPSAB1 was genotyped in a subset of 71 patients.

RESULTS

We found higher accuracy and rates of correctly classified patients for the REMAs (82% and 84%) compared with the NICAS (75% and 75%; P = .02 and P = .03, respectively), particularly among men (P = .05), patients with systemic mastocytosis (P = .05), those presenting anaphylaxis owing to any cause featuring urticaria (P = .04), cardiovascular symptoms (P = .02), and/or presyncope (P = .02) and those with a blood-negative/BM-positive KIT mutational profile (P = .002), but not hereditary α-tryptasemia-associated genotypes. Combined assessment of the REMAs and KIT^D816V in blood yielded an overall improved classification efficiency of 86% versus 84% for REMAs.

CONCLUSIONS

The combined use of the REMAs and blood detection of KIT^D816V is recommended, but more sensitive blood-based molecular assays to detect KIT^D816V are needed.

Idiopathic Anaphylaxis? Analysis of Data from the Anaphylaxis Registry for West Pomerania Province, Poland

The most common causes of anaphylaxis, according to various authors and depending on the age of the studied groups, are: Hymenoptera venom, food, and medications. Unfortunately, we are not always able to indicate the cause of anaphylaxis. There are data in the literature where as many as 41% of all cases are idiopathic anaphylaxis. Since the introduction of new diagnostic methods such as molecular diagnostics (MD) in our centre, the percentage of idiopathic anaphylaxis in the Anaphylaxis Register has significantly decreased. The purpose of this study was to identify possible causes of idiopathic anaphylaxis in patients with a history of moderate to severe anaphylactic reactions. After using MD, the causative agent was found in another 29 people. The proportion of people with idiopathic anaphylaxis in the Registry decreased from 9.2% to 3.5%. There were no significant differences in the incidence, although men appear to be slightly more common in primary idiopathic anaphylaxis. The mean age of primary idiopathic anaphylaxis was 40 years, but this was as high as 51 for anaphylaxis with alpha-gal allergy. Exercise may or may not be present as a cofactor despite its established role, e.g., in wheat-dependent exercise-induced anaphylaxis (WDEIA). In most of the analyzed cases, i.e., 70%, the reaction took place within an hour. The longest time interval from exposure to the development of symptoms is in the case of alpha-gal allergy; in this analysis, it was at least 5 h after ingestion of the so-called "red meat". Patients are not aware of the disease, or further attacks cannot be prevented. As many as 80% had idiopathic anaphylaxis prior to visiting the centre, and 80% developed anaphylaxis after visiting the centre, which emphasizes the need to not stop the medical team in their search for the causes. As many as 93% of cases required medical intervention, of which adrenaline was used only in 34.5%, antihistamines in 86%, systemic glucocorticosteroids (sCS) in 75%, and fluids in 62% of cases. A total of 83% of patients received an emergency kit for self-administration. Idiopathic anaphylaxis can be resolved as known-cause anaphylaxis after a thorough medical history and, if possible, without exposing the patient after using appropriate, modern in vitro diagnostic methods, including molecular diagnostics. The diagnosis of idiopathic anaphylaxis should extend the diagnosis to include alpha-gal syndrome, LTP syndrome and WDEIA.

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.

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.

Refined diagnostic criteria for bone marrow mastocytosis: a proposal of the European competence network on mastocytosis

In the current classification of the World Health Organization (WHO), bone marrow mastocytosis (BMM) is a provisional variant of indolent systemic mastocytosis (ISM) defined by bone marrow involvement and absence of skin lesions. However, no additional diagnostic criteria for BMM have been proposed. Within the registry dataset of the European Competence Network on Mastocytosis, we compared characteristics and outcomes of 390 patients with BMM and 1175 patients with typical ISM. BMM patients were significantly older, predominantly male, had lower tryptase and lower burden of neoplastic mast cells, and displayed a higher frequency of allergic reactions, mainly triggered by Hymenoptera, than patients with typical ISM. The estimated 10-year progression-free survival of BMM and typical ISM was 95.9% and 92.6%, respectively. In BMM patients defined by WHO-based criteria, the presence of one B-Finding and tryptase level ≥125 ng/mL were identified as risk factors for progression in multivariate analyses. BMM patients without any of these risk factors were found to have better progression-free survival (p < 0.05) and better overall survival (p < 0.05) than other ISM patients. These data support the proposal to define BMM as a separate SM variant characterized by SM criteria, absence of skin lesions, absence of B-Findings, and tryptase levels <125 ng/mL.

A Multidisciplinary Diagnostic Approach Reveals a Higher Prevalence of Indolent Systemic Mastocytosis: 15-Years' Experience of the GISM Network

Systemic mastocytosis (SM) and other adult clonal mast cell disorders (CMD) are often underestimated, and their epidemiology data are scarce. We aimed at evaluating the impact of the activity of the Interdisciplinary Group for Study of Mastocytosis (GISM) of Verona on the prevalence and incidence of CMD. We examined the data of 502 adult patients diagnosed with CMD and residing in the Veneto Region, consecutively referred to GISM between 2006 and 2020. SM was diagnosed in 431 cases, while 71 patients had cutaneous mastocytosis or other CMD. Indolent SM represented the most frequent SM variant (91.0%), mainly with the characteristics of bone marrow mastocytosis (54.8%). The prevalence of SM in the adult population of the Veneto region and of the Verona province was 10.2 and 17.2/100,000 inhabitants, respectively. The mean incidence of new SM cases in Verona was 1.09/100,000 inhabitants/year. Hymenoptera venom allergy was the main reason (50%) leading to the CMD diagnosis. Osteoporosis, often complicated by fragility fractures, was present in 35% of cases, even in young patients, especially males. Our data show a higher prevalence and incidence of SM than previously reported, confirming that reference centers with multidisciplinary approach are essential for the recognition and early diagnosis of CMD.

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.

Idiopathic anaphylaxis: Diagnosis and management

Introduction: Idiopathic anaphylaxis (IA) is a diagnosis of exclusion and is based on the inability to identify a causal relationship between a trigger and an anaphylactic event, despite a detailed patient history and careful diagnostic assessment. The prevalence of IA among the subset of people who experienced anaphylaxis is challenging to estimate and varies widely, from 10 to 60%; most commonly noted is ∼20% in the adult anaphylactic population. Comorbid atopic conditions, such as food allergy, allergic rhinitis, and asthma, are present in up to 48% of patients with IA. Improved diagnostic technologies and an increased understanding of conditions that manifest with symptoms associated with anaphylaxis have improved the ability to determine a more accurate diagnosis for patients who may have been initially diagnosed with IA. Methods: Literature search was conducted on PubMed, Google Scholar and Embase. Results: Galactose-α-1,3-galactose (α-gal) allergy, mast cell disorders, and hereditary a-tryptasemia are a few differential diagnoses that should be considered in patients with IA. Unlike food allergy, when anaphylaxis occurs within minutes to 2 hours after allergen consumption, α-gal allergy is a 3-6-hour delayed immunoglobulin E-mediated anaphylactic reaction to a carbohydrate epitope found in red meat (e.g., beef, lamb, pork). The more recently described hereditary α-tryptasemia is an inherited autosomal dominant genetic trait caused by increased germline copies of tryptase human gene alpha-beta 1 (TPSAB1), which encodes α tryptase and is associated with elevated baseline serum tryptase. Acute management of IA consists of carrying an epinephrine autoinjector to be administered immediately at the first signs of anaphylaxis. Long-term management for IA with antihistamines and other agents aims to potentially reduce the frequency and severity of the anaphylactic reactions, although the evidence is limited. Biologics are potentially steroid-sparing for patients with IA; however, more research on IA therapies is needed. Conclusion: The lack of diagnostic criteria, finite treatment options, and intricacies of making a differential diagnosis make IA challenging for patients and clinicians to manage.

Mast cell activation syndrome: is anaphylaxis part of the phenotype? A systematic review

PURPOSE OF REVIEW

Mast cell activation syndrome (MCAS) and anaphylaxis are the result of a spontaneous or triggered pathological degranulation of mast cells (MCs) and might have as substrate normal or pathological MCs (increased burden, aberrant MCs or both).

RECENT FINDINGS

This review summarizes the most recent evidence on immunoglobulin E (IgE)-mediated and non IgE-mediated mechanisms underlying MC activation and degranulation and highlights the importance of standardized diagnostic criteria for MCAS. Application of these criteria implies that in most cases the clinical presentation of MCAS meets the diagnostic criteria for anaphylaxis.

SUMMARY

Integrating clinical parameters and diagnostic test recognition and underlying clonal MC disease are of utmost importance for a patient-tailored approach. Hereditary alpha-tryptasemia can be encountered in context of anaphylaxis, MCAS and primary MC disorders.

Decoding the intricacies of the mast cell compartment

Historically, understanding of the human mast cell (MC) compartment has lagged behind the appreciation of other cell lineages. MCs exist in vascularised tissues but do not under normal circumstances circulate in blood, and there has been no pharmacological agent identified that totally and selectively inhibits human MC function. There are no substantiated accounts of an apparently healthy individual who is severely lacking in MCs. Thus, some of the approaches employed to understand the function of a specific immune cell are not available to the MC biologist. The disease categories that have provided the greatest insight into MC biology have been monoclonal and IgE-mediated MC disorders. This has led to the categorisation of MC diseases as intrinsic or extrinsic to the MC compartment and to the recognition of the role of mediators in MC activation disorders. Mastocytosis as a clonal disorder not only impacts the MC compartment through changes intrinsic to the MC, but also by the effects of episodes of significant release of MC mediators. The availability of newer therapeutic approaches developed to treat monoclonal MC disorders offer insights into how to more selectively approach management of MC centric diseases.

Selecting the Right Criteria and Proper Classification to Diagnose Mast Cell Activation Syndromes: A Critical Review

In recent years, knowledge about mechanisms underlying mast cell activation (MCA) and accumulation in various pathologic conditions increased substantially. In addition, criteria and a classification of MCA syndromes (MCASs) have been set forth. MCAS is defined by typical clinical symptoms, a substantial increase in serum tryptase level during an attack over the patient's baseline tryptase, and a response of the symptoms to drugs targeting mast cells, mediator production, and/or mediator effects. Alternative diagnostic criteria of MCAS have also been suggested, but these alternative criteria often lack specificity and validation. In this report, we critically review the contemporary literature relating to MCAS and compare the specificity, sensitivity, and strength of MCAS-related parameters within proposals to diagnose and classify MCAS and its variants. Furthermore, we highlight the need to apply specific consensus criteria in the evaluation and classification of MCAS in individual patients. This is an urgent and important medical necessity because as an increasing number of patients are being given a misdiagnosis of MCAS based on nonspecific criteria, which contributes to confusion and frustration by patients and caregivers and sometimes may delay recognition and treatment of correct medical conditions that often turn out to be unrelated to MCA.

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.

Bone Marrow Mastocytosis: A Diagnostic Challenge

Bone marrow mastocytosis (BMM) represents a provisional, indolent subvariant of systemic mastocytosis (SM). Utilizing WHO criteria, BMM requires bone marrow (BM) involvement and the absence of mastocytosis skin lesions. BMM is characterized by male sex prevalence, a slight increase of serum tryptase levels, low BM mast cells (MC) burden, and an indolent clinical course. BMM shows a strong correlation with severe anaphylaxis, mainly due to an IgE-mediated allergy to bee or wasp venom and, less frequently, to unexplained (idiopathic) anaphylaxis. Furthermore, BMM is often associated with osteoporosis which could be the only presenting symptom of the disease. BMM is an undervalued disease as serum tryptase levels are not routinely measured in the presence of unexplained osteoporosis or anaphylaxis. Moreover, BMM patients are often symptom-free except for severe allergic reactions. These factors, along with typical low BM MCs infiltration, may contribute to physicians overlooking BMM diagnosis, especially in medical centers that lack appropriately sensitive diagnostic techniques. This review highlights the need for a correct diagnostic pathway to diagnose BMM in patients with suspected symptoms but lacking typical skin lesions, even in the case of normal serum tryptase levels. Early diagnosis may prevent potential life-threatening anaphylaxis or severe skeletal complications.

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.

Comorbidities and Cofactors of Anaphylaxis in Patients with Moderate to Severe Anaphylaxis. Analysis of Data from the Anaphylaxis Registry for West Pomerania Province, Poland

Anaphylaxis is a severe, potentially life-threatening systemic hypersensitivity reaction that is still rarely diagnosed. For safety reasons, patients should visit an allergologist to identify potential causes and cofactors of this reaction. This paper presents the analysis of data from the Anaphylaxis Registry gathered over ten years at the Allergy Clinic, Pomeranian Medical University (PMU). A questionnaire-based survey was used for patients visiting the Allergy Clinic to identify potential augmentation factors/comorbidities and/or cofactors of anaphylaxis in patients with a history of moderate to severe anaphylaxis. The registry comprised patients with grade II or higher anaphylaxis. The gathered data concerned chronic comorbidities (cardiovascular diseases, respiratory diseases, and others), recurrence of anaphylaxis, and potential cofactors in anaphylaxis. In the analyzed group, the incidence rate of anaphylaxis was the highest for women aged 19–60 years. Most common comorbidities in patients with moderate to severe anaphylaxis included: cardiovascular diseases, respiratory tract diseases, features of atopy, and thyroid diseases. More than 30% of drug-induced reactions were anaphylactic reactions due to the re-exposure to the same drug, which points to the need for educational initiatives in this area. The incidence rate of anaphylaxis induced by Hymenoptera stings was comparable in patients who had a previous generalized reaction and those who had good tolerance to the previous sting. It is important to take these cofactors into consideration when evaluating patients with anaphylaxis as they may play a role in future anaphylactic reactions.

Diagnosis, Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine

Mast cell activation (MCA) is seen in a variety of clinical contexts and pathologies, including IgE-dependent allergic inflammation, other immunologic and inflammatory reactions, primary mast cell (MC) disorders, and hereditary alpha tryptasemia (HAT). MCA-related symptoms range from mild to severe to life-threatening. The severity of MCA-related symptoms depends on a number of factors, including genetic predisposition, the number and releasability of MCs, organs affected, and the type and consequences of comorbid conditions. In severe systemic reactions, MCA is demonstrable by a substantial increase of basal serum tryptase levels above the individual’s baseline. When, in addition, the symptoms are recurrent, involve more than one organ system, and are responsive to therapy with MC-stabilizing or mediator-targeting drugs, the consensus criteria for the diagnosis of MCA syndrome (MCAS) are met. Based on the etiology of MCA, patients can further be classified as having i) primary MCAS where KIT-mutated, clonal, MCs are detected; ii) secondary MCAS where an underlying IgE-dependent allergy or other reactive MCA-triggering pathology is found; or iii) idiopathic MCAS, where neither a triggering reactive state nor KIT-mutated MCs are identified. Most severe MCA events occur in combined forms of MCAS, where KIT-mutated MCs, IgE-dependent allergies and sometimes HAT are detected. These patients may suffer from life-threatening anaphylaxis and are candidates for combined treatment with various types of drugs, including IgE-blocking antibodies, anti-mediator-type drugs and MC-targeting therapy. In conclusion, detailed knowledge about the etiology, underlying pathologies and co-morbidities is important to establish the diagnosis and develop an optimal management plan for MCAS, following the principles of personalized medicine.

Insect Sting Anaphylaxis-Or Mastocytosis-Or Something Else?

Insect sting anaphylaxis and mast cell disorders are intertwined in a specific and unusual way. There may be specific subsets of clonal mast cell disorders that are predisposed to sting anaphylaxis. The clinical characteristics of the sting reactions should raise suspicion of underlying mastocytosis (eg, hypotension without hives especially in a male). A baseline serum tryptase level is helpful in the evaluation of patients with insect sting anaphylaxis because it correlates with important risks for these patients, and they have a high frequency of abnormally elevated baseline levels. Elevated baseline serum tryptase level has been reported to correlate with clonal mast cell disease in patients with insect sting anaphylaxis but may also indicate one of several possible underlying syndromes, including mast cell activation syndrome (MCAS), familial hypertryptasemia, and idiopathic anaphylaxis. There is some overlap in these conditions, so it is important to evaluate the clinical pattern at presentation as well as laboratory markers, and to consider bone marrow biopsy to make a final and specific diagnosis of clonal mast cell disease. The presence of venom-IgE does not prove that the patient's previous sting reactions were IgE-mediated, but even low levels of venom-IgE in patients with mastocytosis predispose to severe sting anaphylaxis. Evaluation of all these possible factors will affect the recommendation for venom immunotherapy.

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.

Serum Baseline Tryptase Level as a Marker for the Severity of Anaphylaxis

BACKGROUND

Anaphylaxis is a severe and potentially fatal allergic disease or hypersensitivity reaction with variable clinical presentation. Biomarkers in anaphylaxis could be useful to improve diagnosis, to allow endotyping of patients, and to predict risk.

OBJECTIVE

To investigate the role of serum basal tryptase (sBT) levels in the management of patients with anaphylaxis.

METHODS

Patients with at least 1 episode of anaphylaxis were selected among those who attended the Allergy Clinics of the Clinical Hospital of the Ribeirão Preto Medical School, University of São Paulo, Brazil, upon evaluation by allergy/immunology specialists of our medical staff. Demographic and clinical data were obtained using a structured questionnaire. sBT levels were determined using the ImmunoCAP Tryptase immunoassay.

RESULTS

57 patients (56.1% female) with a median age of 35 years (range 7-87 years) participated in the study. sBT levels ranged from 2.57 to 21.19 ng/mL (mean 5.17 ng/mL), with no significant differences in patients with anaphylaxis due to different triggers. Mean levels were 4.93; 5.2; 5.41, and 5.24 ng/mL for patients who had anaphylaxis due to Hymenoptera venom (n = 17), foods (n = 13), drugs (n = 13), and idiopathic disease (n = 14), respectively. Significantly higher sBT levels were observed in patients with severe anaphylaxis (grade IV) than in patients with mild-moderate disease (grades II/III) (mean levels 6.61 vs. 4.71 ng/mL, respectively).

CONCLUSION

High sBT levels may help to identify patients at increased risk of more severe anaphylaxis, prompting physicians to initiate immediate therapy to avoid further acute episodes.

Idiopathic anaphylaxis

Idiopathic anaphylaxis (IA) or spontaneous anaphylaxis is a diagnosis of exclusion when no cause can be identified. The exact incidence and prevalence of IA are not known. The clinical manifestations of IA are similar to other known causes of anaphylaxis. A typical attack is usually acute in onset and can worsen over minutes to a few hours. The pathophysiology of IA has not yet been fully elucidated, although an IgE-mediated pathway by hitherto unidentified trigger/s might be the main underlying mechanism. Elevated concentrations of urinary histamine and its metabolite, methylimidazole acetic acid, plasma histamine and serum tryptase have been reported, consistent with mast cell activation. There is some evidence that corticosteroids reduce the frequency and severity of episodes of IA, consistent with a steroid-responsive condition. Important differential diagnoses of IA include galactose alpha-1,3 galactose (a carbohydrate contained in red meat) allergy, pigeon tick bite (Argax reflexus), wheat-dependent exercise-induced anaphylaxis, Anisakis simplex allergy and mast cell disorders. Other differential diagnoses include "allergy-mimics" such as asthma masquerading as anaphylaxis, undifferentiated somatoform disorder, panic attacks, globus hystericus, vocal cord dysfunction, scombroid poisoning, vasoactive amine intolerance, carcinoid syndrome and phaeochromocytoma. Acute treatment of IA is the same as for other forms of anaphylaxis. Long-term management is individualized and dictated by frequency and severity of symptoms and involves treatment with H1 and H2 receptor blockers, leukotriene receptor antagonist and consideration for prolonged reducing courses of oral corticosteroids. Patients should possess an epinephrine autoinjector with an anaphylaxis self-management plan. There are anecdotal reports regarding the use of omalizumab. For reasons that remain unclear, the prognosis of IA is generally favourable with appropriate treatment and patient education. If remission cannot be achieved, the diagnosis should be reconsidered.

Proposed Diagnostic Algorithm for Patients with Suspected Mast Cell Activation Syndrome

Mast cell activation (MCA) accompanies diverse physiologic and pathologic processes and is one of the more frequently encountered conditions in medicine. MCA-related symptoms are usually mild and often transient. In such cases, histamine receptor blockers and other mediator-targeting drugs can usually control MCA. In severe cases, an MCA syndrome (MCAS) may be diagnosed. However, overt MCAS is an unusual condition, and many patients referred because of suspected MCAS are diagnosed with other diseases (autoimmune, neoplastic, or infectious) unrelated to MCA or suffer from MCA-related (eg, allergic) disorders and/or comorbidities without fulfilling criteria of an overt MCAS. These considerations are important as more and more patients are informed that they may have MCA or even MCAS without completing a thorough medical evaluation. In fact, in several instances, symptoms are misinterpreted as MCA/MCAS, and other clinically relevant conditions are not thoroughly pursued. The number of such referrals is increasing. To avoid such unnecessary referrals and to prevent misdiagnoses, we here propose a diagnostic algorithm through which a clinically relevant (systemic) MCA can be suspected and MCAS can subsequently be documented or excluded. In addition, the algorithm proposed should help guide the investigating care providers to consider the 2 principal diagnoses that may underlie MCAS, namely, severe allergy and systemic mastocytosis accompanied by severe MCA. Although validation is required, we anticipate that this algorithm will facilitate the management of patients with suspected MCAS.

Adverse reactions to drugs and biologics in patients with clonal mast cell disorders: A Work Group Report of the Mast Cells Disorder Committee, American Academy of Allergy, Asthma & Immunology

Providers caring for patients with mastocytosis are tasked with the decision to consider therapeutic options. This can come with some trepidation because information available in the public domain lists numerous mast cell (MC) activators based on data that do not discriminate between primates, rodents, and MC lines; do not consider dosage; and do not take into account previous exposure and resultant clinical findings. This being said, there is support in the literature for an enhanced MC response in some patients with mastocytosis and in cases in which there is a greater incidence of adverse reactions associated with certain antigens, such as venoms and drugs. Thus this report provides a comprehensive guide for those providers who must decide on therapeutic options in the management of patients with clonal MC disease.

Development and validation of the mastocytosis activity score

BACKGROUND

Mastocytosis is a heterogeneous disease characterized by a clonal expansion of mast cells in various organs. The vast majority of patients suffer from signs and symptoms caused by mediator release from mast cells. Although the disease burden is high, there is currently no specific and validated instrument to measure and monitor signs and symptoms in patients with mastocytosis.

OBJECTIVE

To develop and validate a disease-specific tool to measure and monitor the activity of signs and symptoms in patients with mastocytosis, the Mastocytosis Activity Score (MAS).

METHODS

Nineteen potential MAS items were developed in a combined approach consisting of semi-structured patient interviews, expert input and literature research. Item selection was performed by impact analysis with 76 patients followed by a review for face validity. The resulting MAS was tested for validity, reliability and influence factors. In parallel, a US American English version of the MAS was developed.

RESULTS

A total of 68 mastocytosis patients took part in the MAS validation study. The final 9-item MAS was found to have a three-domain structure ("skin," "gastrointestinal tract" and "other"), a valid total score and an excellent test-retest reliability. Multiple regression analysis revealed that disease duration, age or gender is not a significant determinant of the MAS results.

CONCLUSIONS

The MAS is a disease-specific, valid and reliable patient-reported outcome measure for adult patients with cutaneous and indolent systemic mastocytosis. It may serve as a valuable tool to measure and monitor mastocytosis activity, both, in clinical trials and in routine care.

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.

Proposed Terminology and Classification of Pre-Malignant Neoplastic Conditions: A Consensus Proposal

Cancer evolution is a step-wise non-linear process that may start early in life or later in adulthood, and includes pre-malignant (indolent) and malignant phases. Early somatic changes may not be detectable or are found by chance in apparently healthy individuals. The same lesions may be detected in pre-malignant clonal conditions. In some patients, these lesions may never become relevant clinically whereas in others, they act together with additional pro-oncogenic hits and thereby contribute to the formation of an overt malignancy. Although some pre-malignant stages of a malignancy have been characterized, no global system to define and to classify these conditions is available. To discuss open issues related to pre-malignant phases of neoplastic disorders, a working conference was organized in Vienna in August 2015. The outcomes of this conference are summarized herein and include a basic proposal for a nomenclature and classification of pre-malignant conditions. This proposal should assist in the communication among patients, physicians and scientists, which is critical as genome-sequencing will soon be offered widely for early cancer-detection.

Insights in Anaphylaxis and Clonal Mast Cell Disorders

The prevalence of anaphylaxis among patients with clonal mast cell disorders (MCD) is clearly higher comparing to the general population. Due to a lower frequency of symptoms outside of acute episodes, clonal MCD in the absence of skin lesions might sometimes be difficult to identify which may lead to underdiagnosis, and anaphylaxis is commonly the presenting symptom in these patients. Although the release of mast cell (MC) mediators upon MC activation might present with a wide variety of symptoms, particular clinical features typically characterize MC mediator release episodes in patients with clonal MCD without skin involvement. Final diagnosis requires a bone marrow study, and it is recommended that this should be done in reference centers. In this article, we address the main triggers for anaphylaxis, risk factors, clinical presentation, diagnosis, and management of patients with MC activation syndromes (MCASs), with special emphasis on clonal MCAS [systemic mastocytosis and mono(clonal) MC activations syndromes].

Systemic mastocytosis with KIT V560G mutation presenting as recurrent episodes of vascular collapse: response to disodium cromoglycate and disease outcome

Background

Mastocytosis are rare diseases characterized by an accumulation of clonal mast cells (MCs) in one or multiple organs or tissues. Patients with systemic mastocytosis (SM), whose MCs frequently arbor the activating D816V KIT mutation, may have indolent to aggressive diseases, and they may experience MC mediator related symptoms. Indolent SM with recurrent anaphylaxis or vascular collapse in the absence of skin lesions, ISMs(−), is a specific subtype indolent SM (ISM), and this clonal MC activation disorder represents a significant fraction of all MC activation syndromes. The V560G KIT mutation is extremely rare in patients with SM and its biological and prognostic impact remains unknown.

Case presentation

A 15-year old boy was referred to our hospital because of repeated episodes of flushing, hypotension and syncope since the age of 3-years, preceded by skin lesions compatible with mastocytosis on histopathology that had disappeared in the late-early childhood. Diagnosis of ISM, more precisely the ISMs(−) variant, was confirmed based on the clinical manifestations together with increased baseline serum tryptase levels and the presence of morphologically atypical, mature appearing (CD117+high, FcεRI+) phenotypically aberrant (CD2+, CD25+) MCs, expressing activation-associated markers (CD63, CD69), in the bone marrow. Molecular genetic studies revealed the presence of the KIT V560G mutation in bone marrow MCs, but not in other bone marrow cells, whereas the screening for mutations in codon 816 of KIT was negative. The patient was treated with oral disodium cromoglycate and the disease had a favorable outcome after an eleven-year follow-up period, during which progressively lower serum tryptase levels together with the fully disappearance of all clinical manifestations was observed.

Conclusions

To the best of our knowledge this first report of a patient with ISM, whose bone marrow MCs carry the KIT V560G activating mutation, manifesting as recurrent spontaneous episodes of flushing and vascular collapse in the absence of skin lesions at the time of diagnosis, in whom disodium cromoglycate had led to long term clinical remission.

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.

Diagnosis of exercise-induced anaphylaxis: current insights

Exercise-induced anaphylaxis (EIAn) is defined as the occurrence of anaphylactic symptoms (skin, respiratory, gastrointestinal, and cardiovascular symptoms) after physical activity. In about a third of cases, cofactors, such as food intake, temperature (warm or cold), and drugs (especially nonsteroidal anti-inflammatory drugs) can be identified. When the associated cofactor is food ingestion, the correct diagnosis is food-dependent EIAn (FDEIAn). The literature describes numerous reports of FDEIAn after intake of very different foods, from vegetables and nuts to meats and seafood. One of the best-characterized types of FDEIAn is that due to ω5-gliadin of wheat, though cases of FDEIAn after wheat ingestion by sensitization to wheat lipid transfer protien (LTP) are described. Some pathophysiological mechanisms underlying EIAn have been hypothesized, such as increase/alteration in gastrointestinal permeability, alteration of tissue transglutaminase promoting IgE cross-linking, enhanced expression of cytokines, redistribution of blood during physical exercise leading to altered mast-cell degranulation, and also changes in the acid–base balance. Nevertheless, until now, none of these hypotheses has been validated. The diagnosis of EIAn and FDEIAn is achieved by means of a challenge, with physical exercise alone for EIAn, and with the assumption of the suspected food followed by physical exercise for FDEIAn; in cases of doubtful results, a double-blind placebo-controlled combined food–exercise challenge should be performed. The prevention of this particular kind of anaphylaxis is the avoidance of the specific trigger, ie, physical exercise for EIAn, the assumption of the culprit food before exercise for FDEIAn, and in general the avoidance of the recognized cofactors. Patients must be supplied with an epinephrine autoinjector, as epinephrine has been clearly recognized as the first-line intervention for anaphylaxis.

Developments in the field of allergy in 2014 through the eyes of Clinical and Experimental Allergy

The pathogenesis of asthma continues to be a major topic of interest to our authors with reviews and original papers on the role of viruses, mechanisms of inflammation, biomarkers, and phenotypes of asthma being major topics. A number of papers described new treatments for asthma focusing on blocking the Th2 response reflecting the fact that two decades of work in this area is finally bearing fruit. The pathogenesis of chronic rhinosinusitis is a growing area of interest, but there has been less on the genetics of airways disease than in previous years possibly reflecting the degree of rigour (and therefore a smaller body of work), with which these sorts of studies are now being undertaken. There continues to be a wide range of papers dealing with mechanisms of allergic disease ranging from clinical-based studies to basic research and the use of in vivo animal models especially mice. As before, mechanisms and new approaches to immunotherapy are common themes. Several were published in the allergens section investigating modification of allergens to increase their effectiveness and reduce the risk of adverse events. Risk factors for allergic disease was a common theme in the epidemiology section and food allergy a common theme in clinical allergy with papers on the development of protocols to induce tolerance and attempts to find biomarkers to distinguish sensitization from allergic disease. This was another exciting year for the editors, and we hope the readers of the journal.

Transgenerational transmission of systemic mast cell activation disease-genetic and epigenetic features

Systemic mast cell activation disease (MCAD) comprises disorders characterized by an enhanced release of mast cell mediators accompanied by a varying accumulation of dysfunctional mast cells. Within the last years, evidence has been presented that MCAD is a multifactorial polygenic determined disease with the KIT(D816V) mutation and its induced functional consequences considered as special case. The respective genes encode proteins for various signaling pathways, epigenetic regulators, the RNA splicing machinery, and transcription factors. Transgenerational transmission of MCAD appears to be quite common. The basics of the molecular mechanisms underlying predisposition of the disease, that is, somatic and germline mutations and the contribution of epigenetic processes have become identifiable. The aim of the present review is to present and discuss available genetic, epigenetic and epidemiological findings, and to present a model of MCAD pathogenesis.