Definitions, criteria and global classification of mast cell disorders with special reference to mast cell activation syndromes: a consensus proposal

Idiopathic anaphylaxis yardstick: Practical recommendations for clinical practice

Anaphylaxis is considered idiopathic when there is no known trigger. The signs and symptoms of idiopathic anaphylaxis (IA) are identical to those of anaphylaxis because of a known cause and can include cutaneous, circulatory, respiratory, gastrointestinal, and neurologic symptoms. Idiopathic anaphylaxis can be a frustrating disease for patients and health care providers. Episodes are unpredictable, and differential diagnosis is challenging. Current anaphylaxis guidelines have little specific guidance regarding differential diagnosis and long-term management of IA. Therefore, the objective of the Idiopathic Anaphylaxis Yardstick is to use published data and the authors' combined clinical experience to provide practical recommendations for the diagnosis and management of patients with IA.

An update on allergy and anaphylaxis in pediatric anesthesia

Childhood allergy is common, and increasing. Many children are incorrectly labeled as having allergy or adverse drug reactions. This can pose a dilemma for anesthetists and lead to a change in practice or drug selection. We review the pathophysiology of hypersensitivity reactions and the implications for anesthesia of food allergy, atopy, and family history of allergy in children. The epidemiology of anaphylaxis is discussed. We discuss the common triggers of perioperative anaphylaxis in children and explore emerging triggers including chlorhexidine and sugammadex. Accurate data on pediatric perioperative anaphylaxis is limited worldwide, with marked geographic variation. This highlights the need for accurate local, district and/or nationwide incident reporting. The clinical features, diagnosis, and management of anaphylaxis under anesthesia are discussed. We review the process of expert allergy testing following a suspected case of anaphylaxis to guide future safe anesthesia administration. The preoperative consultation is an opportunity for referral for allergy testing to allow de-labeling. This has the potential for improved antibiotic stewardship and more effective treatment with first-line therapeutic agents.

Improvement of the Elevated Tryptase Criterion to Discriminate IgE- From Non-IgE-Mediated Allergic Reactions

BACKGROUND

Differentiating between immunoglobulin E (IgE)-dependent and IgE-independent hypersensitivity reactions may improve the etiologic orientation and clinical management of patients with allergic reactions in the anesthesia setting. Serum tryptase levels may be useful to discriminate the immune mechanism of allergic reactions, but the diagnostic accuracy and optimal cutpoint remain unclear.We aimed to compare the diagnostic accuracy of tryptase during reaction (TDR) alone and the TDR/basal tryptase (TDR/BT) ratio for discriminating IgE- from non-IgE-mediated allergic reactions, and to estimate the best cut point for these indicators.

METHODS

We included 111 patients (45% men; aged 3-99 years) who had experienced an allergic reaction, even though the allergic reaction could be nonanaphylactic. Allergy tests were performed to classify the reaction as an IgE- or non-IgE-mediated one. The area under the curve (AUC) of the receiver operating characteristic analysis was performed to estimate the discriminative ability of TDR and TDR/BT ratio.

RESULTS

An IgE-mediated reaction was diagnosed in 49.5% of patients, and 56% of patients met anaphylaxis criteria. The median (quartiles) TDR for the IgE-mediated reactions was 8.0 (4.9-19.6) and 5.1 (3.5-8.1) for the non-IgE-mediated (P = .022). The median (quartiles) TDR/BT ratio was 2.7 (1.7-4.5) in IgE-mediated and 1.1 (1.0-1.6) in non-IgE-mediated reactions (P < .001). The TDR/BT ratio showed the greatest ability to discriminate IgE- from non-IgE-mediated reactions compared to TDR (AUC TDR/BT = 0.79 [95% confidence interval (CI), 0.70-0.88] and AUC TDR = 0.66 [95% CI, 0.56-0.76]; P = .001). The optimal cut point for TDR/BT (maximization of the sum of the sensitivity and specificity) was 1.66 (95% CI, 1.1-2.2).

CONCLUSIONS

The TDR/BT ratio showed a significantly better discriminative ability than TDR to discriminate IgE- from non-IgE-mediated allergic reactions. An optimal TDR/BT ratio threshold of approximately 1.66 may be useful in clinical practice to classify allergic reactions as IgE- or non-IgE-mediated.

Why the 20% + 2 Tryptase Formula Is a Diagnostic Gold Standard for Severe Systemic Mast Cell Activation and Mast Cell Activation Syndrome

Mast cell activation syndrome (MCAS) is a condition characterized by recurrent episodes of clinically relevant, systemic, severe reactions to mast cell (MC)-derived mediators released in the context of anaphylaxis or another acute MC-related event. It is important to document MC involvement in these reactions in order to establish the diagnosis MCAS. The most specific and reliable marker of systemic MC activation is an acute and substantial event-related (transient) increase in the serum tryptase level over the individual's baseline value. However, the baseline level of tryptase varies depending on the underlying disease and the genetic background. For example, an estimated 3-5% of healthy individuals exhibit duplications or multiple copies of the TPSAB1 gene encoding for alpha-tryptase, and over 30% of all patients with myeloid neoplasms, including mastocytosis, have elevated basal tryptase levels. Therefore, it is of utmost importance to adjust the event-related diagnostic (MCAS-confirming) increase in tryptase over the individual baseline in a robust approach. To address this challenge, the 20% + 2 formula was proposed by the consensus group in 2012. Since then, this approach has been validated in clinical practice by independent groups and found to be sound. In the current article, we discuss the emerging importance and value of the 20% + 2 formula in clinical practice and its role as a criterion of severe systemic MC activation and MCAS.

Multidisciplinary Challenges in Mastocytosis and How to Address with Personalized Medicine Approaches

Mastocytosis is a hematopoietic neoplasm defined by abnormal expansion and focal accumulation of clonal tissue mast cells in various organ-systems. The disease exhibits a complex pathology and an equally complex clinical behavior. The classification of the World Health Organization (WHO) divides mastocytosis into cutaneous forms, systemic variants, and localized mast cell tumors. In >80% of patients with systemic mastocytosis (SM), a somatic point mutation in KIT at codon 816 is found. Whereas patients with indolent forms of the disease have a normal or near-normal life expectancy, patients with advanced mast cell neoplasms, including aggressive SM and mast cell leukemia, have a poor prognosis with short survival times. In a majority of these patients, multiple somatic mutations and/or an associated hematologic neoplasm, such as a myeloid leukemia, may be detected. Independent of the category of mastocytosis and the serum tryptase level, patients may suffer from mediator-related symptoms and/or osteopathy. Depending on the presence of co-morbidities, the symptomatology in such patients may be mild, severe or even life-threatening. Most relevant co-morbidities in such patients are IgE-dependent allergies, psychiatric, psychological or mental problems, and vitamin D deficiency. The diagnosis and management of mastocytosis is an emerging challenge in clinical practice and requires vast knowledge, a multidisciplinary approach, and personalized medicine procedures. In this article, the current knowledge about mastocytosis is reviewed with special emphasis on the multidisciplinary aspects of the disease and related challenges in daily practice.

Recent advances in our understanding of mast cell activation - or should it be mast cell mediator disorders?

INTRODUCTION

An increasing number of patients present with multiple symptoms affecting many organs including the brain due to multiple mediators released by mast cells. These unique tissue immune cells are critical for allergic reactions triggered by immunoglobulin E (IgE), but are also stimulated (not activated) by immune, drug, environmental, food, infectious, and stress triggers, leading to secretion of multiple mediators often without histamine and tryptase. The presentation, diagnosis, and management of the spectrum of mast cell disorders are very confusing. As a result, neuropsychiatric symptoms have been left out, and diagnostic criteria made stricter excluding most patients. Areas covered: A literature search was performed on papers published between January 1990 and November 2018 using MEDLINE. Terms used were activation, antihistamines, atopy, autism, brain fog, heparin, KIT mutation, IgE, inflammation, IL-6, IL-31, IL-37, luteolin, mast cells, mastocytosis, mediators, mycotoxins, release, secretion, tetramethoxyluteolin, and tryptase. Expert opinion: Conditions associated with elevated serum or urine levels of any mast cell mediator, in the absence of comorbidities that could explain elevated levels, should be considered 'Mast Cell Mediator Disorders (MCMD).' Emphasis should be placed on the identification of unique mast cell mediators, and development of drugs or supplements that inhibit their release.

Paired acute-baseline serum tryptase levels in perioperative anaphylaxis: An observational study

BACKGROUND

Anaphylaxis is recognized mainly through clinical criteria, which may lack specificity or relevance in the perioperative setting. The transient increase in serum tryptase has been proposed since 1989 as a diagnostic tool. Sampling for well-defined acute and baseline determinations has been recommended. We assessed the performance of four proposed algorithms with tightly controlled time frames for tryptase sampling, their robustness with inadequate sampling times, and the possible use of mature tryptase determination.

METHODS

A retrospective study was performed on 102 adult patients from the Aix-Marseille University Hospitals who had experienced a perioperative hypersensitivity reaction clinically suggesting anaphylaxis. EAACI and ICON criteria were used to diagnose anaphylaxis. Mature and total serum tryptase levels were measured.

RESULTS

Based on EAACI guidelines, clinical diagnostic criteria for anaphylaxis were found in 76 patients and lacking in 26. The most effective algorithm was the international consensus recommendation of 2012 that acute total tryptase levels should be greater than ([1.2×baseline tryptase] + 2] μg/L to be considered a clinically significant rise. In our cohort, this algorithm achieved 94% positive predictive value (PPV), 53% negative predictive value (NPV), 75% sensitivity, 86% specificity, and a Youden's index value of 0.61. A detectable acute mature tryptase level showed lower sensitivity, particularly in patients with acute total tryptase levels lower than 16 μg/L. Acute tryptase levels varied as a function of the clinical severity of anaphylaxis.

CONCLUSION

Total tryptase levels in serum discriminated between nonanaphylactic and anaphylactic events in a perioperative setting when acute and baseline levels were collected and analyzed by the consensus algorithm.

Higher prevalence of vertebral fractures in systemic mastocytosis, but not in cutaneous mastocytosis and idiopathic mast cell activation syndrome

Little is known about osteoporosis in mast cell disorders (MCDs) not related to systemic mastocytosis. We described osteoporosis and fractures in MCDs and showed that systemic mastocytosis was the only studied MCDs associated with osteoporotic vertebral fractures.

INTRODUCTION

To describe osteoporosis (OP) and fragility fractures in mast cell disorders (MCDs).

METHODS

We retrospectively analyzed data concerning all successive patients with systemic mastocytosis (SM), cutaneous mastocytosis (CM), and mast cell activation syndromes (MCAS) diagnosed in our mastocytosis expert center between 2004 and 2015. We collected data concerning demographic profiles, clinical signs of MCD, osteoporosis, fractures, densitometry, and biological assessment of MCD. We compared CM and MCAS patients with SM patients with regard to the characteristics of OP and fragility fractures.

RESULTS

We assessed 89 SM patients, 20 CM patients, and 20 MCAS patients. Osteoporosis was less frequent in CM (15.0%) and MCAS (10.0%) than in SM (44.9%). Similarly, fractures were less frequent in non-SM MCDs, respectively 5.0%, 5.0%, and 28.1%. SM patients displayed high prevalence of vertebral fractures (22.5%), mostly multiple. Conversely, in non-SM patients, vertebral fractures appeared to be uncommon (5%) and more frequently associated with risk factors for osteoporosis.

CONCLUSIONS

SM is associated with multiple vertebral osteoporotic fractures, whereas CM and MCAS do not appear to be associated with this phenotype.

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.

The role of mast cells in pediatric gastrointestinal disease

Mast cells are granulocytes derived from CD34+ pluripotent progenitor cells that demonstrate plasticity in their development, leaving the bone marrow and differentiating in the tissue where they ultimately reside. They are best known for their role in the allergic response, but also play a prominent immunoregulatory role in other processes, including immune tolerance, the innate immune response, angiogenesis, wound healing and tissue remodeling. Mast cells are found throughout the gastrointestinal tract; their metabolic products influence and regulate intestinal epithelial and endothelial function, gastrointestinal secretion, intestinal motility and absorption, and contribute to host defense. They also play an important role in the development of visceral hypersensitivity through bidirectional interaction with the enteric nervous system. Mast cells have been found to have an increasingly important role in the pathophysiology of a number of pediatric gastrointestinal diseases. This review summarizes the current understanding of the role that mast cells play in the development of pediatric gastrointestinal disorders, including eosinophilic esophagitis, functional dyspepsia, irritable bowel syndrome, celiac disease, inflammatory bowel disease, histologically negative appendicitis, Hirschsprung’s disease, intestinal neuronal dysplasia, and food protein-induced enterocolitis syndrome.

Biomarkers in Human Anaphylaxis: A Critical Appraisal of Current Evidence and Perspectives

Anaphylaxis is a type I hypersensitivity reaction that is potentially fatal if not promptly treated. It is a clinical diagnosis, although measurement of serial serum total mast cell tryptase (MCT) is gold standard and may help differentiate anaphylaxis from its mimics. The performance characteristics of MCT assays in anaphylaxis has been variable in previous studies, due to multiple factors including differences in the definition of anaphylaxis, methods of MCT interpretation, clinical setting of anaphylaxis, causative agents, and timing of blood sample. An international consensus equation for MCT to interpret mast cell activation has been proposed and recently validated in the context of peri-operative anaphylaxis during general anesthesia. There has been an interest in the detection of newer biomarkers in anaphylaxis including platelet activation factor (PAF), chymase, carboxypeptidase A3, dipeptidyl peptidase I (DPPI), basogranulin, and CCL-2. The key determinants of an ideal biomarker in anaphylaxis are half-life, sample handling and processing requirements, and cost. There may be a role for metabolomics and systems biology in the exploration of novel biomarkers in anaphylaxis. Future studies applying these approaches might provide greater insight into factors determining severity, clinical risk stratification, identification of mast cell disorders and improving our understanding of this relatively complex acute immunological condition. Post mortem MCT evaluation is used in Forensic Medicine during autopsy for cases involving sudden death or suspected anaphylaxis. Interpretation of post mortem MCT is challenging since there is limited published evidence and the test is confounded by multiple variables largely linked to putrefaction and site of sampling. Thus, there is no international consensus on a reference range. In this state of the art review, we will focus on the practical challenges in the laboratory diagnosis of anaphylaxis and critically appraise (a) performance characteristics of MCT in anaphylaxis in different clinical scenarios (b) the role for novel biomarkers and (c) post mortem MCT and its role in fatal anaphylaxis.

Mastocytosis - pathogenesis, clinical manifestation and treatment

The term mastocytosis designates a group of rare disorders characterized by typical skin lesions, frequently associated episodes of anaphylaxis, and clinical symptoms related to the release of various mediators. Dermatologists/allergists are frequently the first to establish the diagnosis. The condition is based on clonal mast cell proliferation, usually in the skin or bone marrow and only rarely in the gastrointestinal tract or other tissues. In general, mastocytosis has a good prognosis in terms of life expectancy. Rare variants - including mast cell leukemia, aggressive mastocytosis, and the exceedingly rare mast cell sarcoma - require cytoreductive therapy. In cases associated with hematological neoplasms, the prognosis depends on the underlying hematologic disorder.

[Surgical interventions in patients with systemic mast cell activation disease : Recommendations for perioperative management]

BACKGROUND

Systemic mast cell activation disease (MCAD, prevalence 5-10%) is a multifactorial, polygenic disease with multisystemic symptoms that is characterized by an unregulated increased release of mast cell mediators and an accumulation of activated mast cells potentially in all organs and tissues. Due to the high prevalence of the disease, physicians involved in surgical, anesthesiological and interventional procedures are often unknowingly faced with MCAD patients experiencing unexpected preoperative, intraoperative and postoperative complications, if no mast cell-specific treatment regimens have been applied.

OBJECTIVE

The findings from a literature search, consensus recommendations of the various international expert groups and extensive own experience in the treatment of MCAD patients enable an empirical and evidence-based care of MCAD patients in association with invasive procedures.

RESULTS AND CONCLUSION

Due to the high prevalence of MCAD in the population, it can be assumed that patients with MCAD are correspondingly frequently represented in the surgical patient collective. When MCAD-specific peculiarities are preventively considered in the anesthesiological and surgical procedures in patients with proven or suspected mast cell disease, MCAD patients should not be classified as being at risk.

Mast cell tryptase - Marker and maker of cardiovascular diseases

Mast cells are tissue-resident cells, which have been proposed to participate in various inflammatory diseases, among them the cardiovascular diseases (CVDs). For mast cells to be able to contribute to an inflammatory process, they need to be activated to exocytose their cytoplasmic secretory granules. The granules contain a vast array of highly bioactive effector molecules, the neutral protease tryptase being the most abundant protein among them. The released tryptase may act locally in the inflamed cardiac or vascular tissue, so contributing directly to the pathogenesis of CVDs. Moreover, a fraction of the released tryptase reaches the systemic circulation, thereby serving as a biomarker of mast cell activation. Actually, increased levels of circulating tryptase have been found to associate with CVDs. Here we review the biological relevance of the circulating tryptase as a biomarker of mast cell activity in CVDs, with special emphasis on the relationship between activation of mast cells in their tissue microenvironments and the pathophysiological pathways of CVDs. Based on the available in vitro and in vivo studies, we highlight the potential molecular mechanisms by which tryptase may contribute to the pathogenesis of CVDs. Finally, the synthetic and natural inhibitors of tryptase are reviewed for their potential utility as therapeutic agents in CVDs.

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.

Biomarkers for evaluation of mast cell and basophil activation

Mast cells and basophils play a pathogenetic role in allergic, inflammatory, and autoimmune disorders. These cells have different development, anatomical location and life span but share many similarities in mechanisms of activation and type of mediators. Mediators secreted by mast cells and basophils correlate with clinical severity in asthma, chronic urticaria, anaphylaxis, and other diseases. Therefore, effective biomarkers to measure mast cell and basophil activation in vivo could potentially have high diagnostic and prognostic values. An ideal biomarker should be specific for mast cells or basophils, easily and reproducibly detectable in blood or biological fluids and should be metabolically stable. Markers of mast cell and basophil include molecules secreted by stimulated cells and surface molecules expressed upon activation. Some markers, such as histamine and lipid mediators are common to mast cells and basophils whereas others, such as tryptase and other proteases, are relatively specific for mast cells. The best surface markers of activation expressed on mast cells and basophils are CD63 and CD203. While these mediators and surface molecules have been associated to a variety of diseases, none of them fulfills requirements for an optimal biomarker and search for better indicators of mast cell/basophil activation in vivo is ongoing.

The Data Registry of the European Competence Network on Mastocytosis (ECNM): Set Up, Projects, and Perspectives

Mastocytosis is a unique hematologic neoplasm with complex biology and pathology and a variable clinical course. The disease can essentially be divided into cutaneous mastocytosis (CM) and systemic mastocytosis (SM). In adults, SM is diagnosed in most cases and manifests as either indolent or advanced disease. Patients with advanced SM have an unfavorable prognosis with reduced survival. However, so far, little is known about the prevalence of various categories of SM and about prognostic factors. In an attempt to learn more about the behavior and evolution of various forms of CM and SM, the European Competence Network on Mastocytosis (ECNM) initiated a mastocytosis registry in 2012. In this article, the set up and start phase of this registry are described. Until 2018, more than 3000 patients from 12 countries and 25 centers have been enrolled. In a majority of all patients, robust follow-up data and relevant clinical end points are available. Using this data set, a series of registry projects have been launched, with the aim to validate previously identified diagnostic and prognostic variables and to identify new disease-related and patient-related parameters in various forms of mastocytosis. Moreover, the core data set of the registry will be useful to establish multiparametric scoring systems through which prognostication and individualized management of patients with mastocytosis should improve in the foreseeable future.

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.

The Italian Mastocytosis Registry: 6-year experience from a hospital-based registry

Aim: We collected ‘real-life’ data on the management of patients with mastocytosis in the Italian Mastocytosis Registry. Methods: Six hundred patients diagnosed with mastocytosis between 1974 and 2014 were included from 19 centers. Results: Among adults (n = 401); 156 (38.9%) patients were diagnosed with systemic mastocytosis. In 212 adults, no bone marrow studies were performed resulting in a provisional diagnosis of mastocytosis of the skin. This diagnosis was most frequently established in nonhematologic centers. In total, 182/184 pediatric patients had cutaneous mastocytosis. We confirmed that in the most patients with systemic mastocytosis, serum tryptase levels were >20 ng/ml and KIT D816V was detectable. Conclusion: The Italian Mastocytosis Registry revealed some center-specific approaches for diagnosis and therapy. Epidemiological evidence on this condition is provided.

Diagnoses and Management of Drug Hypersensitivity and Anaphylaxis in Cancer and Chronic Inflammatory Diseases: Reactions to Taxanes and Monoclonal Antibodies

Due to the increase in utilization of chemotherapies and antibodies, drug hypersensitivity reactions have increased dramatically worldwide, preventing the use of first-line therapies and impacting patients' survival and quality of life. Some of the more frequently used medications in cancer include taxanes for ovarian, lung, breast, and prostate cancers. Monoclonal antibodies are used in the treatment of neoplastic, autoimmune, and inflammatory diseases, and their clinical applications are becoming broader. Monoclonal antibody targets include CD20, HER-2, EGFR, IL-6 receptor, TNF-α, CD30, VEGF-A, IgE, and more, and examples of immune-mediated and inflammatory diseases that respond to monoclonal antibodies include rheumatoid arthritis, Crohn's disease, ulcerative colitis, juvenile idiopathic arthritis, psoriasis and psoriatic arthritis, Wegener's granulomatosis, microscopic polyangiitis, ankylosing spondylitis, plaque psoriasis, and asthma. Neoplastic diseases include non-Hodgkin's lymphoma, chronic lymphocytic leukemia, and colorectal, breast, gastric, and lung cancer. The clinical presentation of drug hypersensitivity reactions ranges from mild cutaneous reactions to life-threatening symptoms including anaphylaxis. Rapid drug desensitization (RDD) has become a groundbreaking approach to the management of immediate drug hypersensitivity reactions IgE and non-IgE mediated. It is the only effective procedure that enables sensitized patients to receive the full treatment dose safely, thus representing an important advance in the patients' treatment and prognosis. The aim of this review is to provide an update on hypersensitivity reactions to commonly used monoclonal and taxanes, their clinical presentations, diagnosis, and the use of RDD for their management.

Comparative oncology: The paradigmatic example of canine and human mast cell neoplasms

In humans, advanced mast cell (MC) neoplasms are rare malignancies with a poor prognosis. Only a few preclinical models are available, and current treatment options are limited. In dogs, MC neoplasms are the most frequent malignant skin tumours. Unlike low‐grade MC neoplasms, high‐grade MC disorders usually have a poor prognosis with short survival. In both species, neoplastic MCs display activating KIT mutations, which are considered to contribute to disease evolution. Therefore, tyrosine kinase inhibitors against KIT have been developed. Unfortunately, clinical responses are unpredictable and often transient, which remains a clinical challenge in both species. Therefore, current efforts focus on the development of new improved treatment strategies. The field of comparative oncology may assist in these efforts and accelerate human and canine research regarding diagnosis, prognostication, and novel therapies. In this article, we review the current status of comparative oncology approaches and perspectives in the field of MC neoplasms.

Bone Marrow Expression of Mast Cell Disorders

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

Sugammadex hypersensitivity and underlying mechanisms: a randomised study of healthy non-anaesthetised volunteers

BACKGROUND

We investigated potential for hypersensitivity reactions after repeated sugammadex administration and explored the mechanism of hypersensitivity.

METHODS

In this double-blind, placebo-controlled study (NCT00988065), 448 healthy volunteers were randomised to one of three arms to receive three repeat i.v. administrations of either sugammadex 4 mg kg^-1, 16 mg kg^-1, or placebo. Primary endpoint was percentage of subjects with hypersensitivity (assessed by an independent adjudication committee). Secondary endpoint of anaphylaxis was classified per Sampson and Brighton criteria. Exploratory endpoints included skin testing, serum tryptase, anti-sugammadex antibodies [immunoglobulin (Ig) E/IgG], and other immunologic parameters.

RESULTS

Hypersensitivity was adjudicated for 1/148 (0.7%), 7/150 (4.7%), and 0/150 (0.0%) subjects after sugammadex 4 mg kg^-1, 16 mg kg^-1, and placebo, respectively. After sugammadex 16 mg kg^-1, one subject met Sampson criterion 1 and Brighton level 1 (highest certainty) anaphylaxis criteria; two met Brighton level 2 criteria. After database lock it was determined that certain protocol deviations could have introduced bias in the reporting of hypersensitivity signs/symptoms in a subject subset. Objective laboratory investigations indicated that potential underlying hypersensitivity mechanisms were unlikely to have been activated; the results suggest that most of the observed hypersensitivity reactions were unlikely IgE/IgG-mediated.

CONCLUSION

Dose-dependent hypersensitivity or anaphylaxis reactions to sugammadex were observed when administered without prior neuromuscular blocking agent. Laboratory investigations do not suggest prevalent allergen-specific IgE/IgG-mediated immunologic hypersensitivity. Because it could not be fully excluded that estimates of hypersensitivity/anaphylaxis incidence were unbiased, an additional study was conducted to characterise the potential for hypersensitivity reactions and is described in a companion report.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov NCT00988065; Protocol number P06042.

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.

Immediate Hypersensitivity to Contrast Agents: The French 5-year CIRTACI Study

BACKGROUND

Iodinated and gadolinium-based contrast media (ICM; GBCM) induce immediate hypersensitivity (IH) reactions. Differentiating allergic from non-allergic IH is crucial; allergy contraindicates the culprit agent for life. We studied frequency of allergic IH among ICM or GBCM reactors.

METHODS

Patients were recruited in 31 hospitals between 2005 and 2009. Clinical symptoms, plasma histamine and tryptase concentrations and skin tests were recorded. Allergic IH was diagnosed by intradermal tests (IDT) with the culprit CM diluted 1:10, "potentially allergic" IH by positive IDT with pure CM, and non-allergic IH by negative IDT.

FINDINGS

Among 245 skin-tested patients (ICM = 209; GBCM = 36), allergic IH to ICM was identified in 41 (19.6%) and to GBCM in 10 (27.8%). Skin cross-reactivity was observed in 11 patients with ICM (26.8%) and 5 with GBCM (50%). Allergy frequency increased with clinical severity and histamine and tryptase concentrations (p < 0.0001). Cardiovascular signs were strongly associated with allergy. Non-allergic IH was observed in 152 patients (62%) (ICM:134; GBCM:18). Severity grade was lower (p < 0.0001) and reaction delay longer (11.6 vs 5.6 min; p < 0.001). Potentially allergic IH was diagnosed in 42 patients (17.1%) (ICM:34; GBCM:8). The delay, severity grade, and mediator release were intermediate between the two other groups.

INTERPRETATION

Allergic IH accounted for < 10% of cutaneous reactions, and > 50% of life-threatening ones. GBCM and ICM triggered comparable IH reactions in frequency and severity. Cross-reactivity was frequent, especially for GBCM. We propose considering skin testing with pure contrast agent, as it is more sensitive than the usual 1:10 dilution criteria.

Management of a Parturient with Mast Cell Activation Syndrome: An Anesthesiologist's Experience

Mast cell activation syndrome (MCAS) is a disorder in which patients experience symptoms and signs attributable to inappropriate mast cell activation and mediator release. Multiorgan involvement in patients can result in significant morbidity and possible mortality. Limited literature exists regarding anesthetic management of patients with MCAS. We report a case of vaginal delivery with neuraxial labor analgesia in a parturient with this condition and highlight the importance of multidisciplinary planning for uneventful outcomes. Stress can trigger life-threatening symptoms, and counseling is important to allay patients' fears. Optimum medical control, adequate premedication, avoidance of triggers, and preparedness to treat serious mediator effects are key. We review MCAS and discuss anesthetic considerations for patients with this mast cell disorder.