Decoding the Genetic Basis of Mast Cell Hypersensitivity and Infection Risk in Hypermobile Ehlers-Danlos Syndrome.

Hypermobile Ehlers-Danlos syndrome (hEDS) is a connective tissue disorder marked by joint hypermobility, skin hyperextensibility, and tissue fragility. Recent studies have linked hEDS with mast cell activation syndrome (MCAS), suggesting a genetic interplay affecting immune regulation and infection susceptibility. This study aims to decode the genetic basis of mast cell hypersensitivity and increased infection risk in hEDS by identifying specific genetic variants associated with these conditions. We conducted whole-genome sequencing (WGS) on 18 hEDS participants and 7 first-degree relatives as controls, focusing on identifying genetic variants associated with mast cell dysregulation. Participants underwent clinical assessments to document hEDS symptoms and mast cell hypersensitivity, with particular attention to past infections and antihistamine response. Our analysis identified specific genetic variants in MT-CYB, HTT, MUC3A, HLA-B and HLA-DRB1, which are implicated in hEDS and MCAS. Protein-protein interaction (PPI) network analysis revealed significant interactions among identified variants, highlighting their involvement in pathways related to antigen processing, mucosal protection, and collagen synthesis. Notably, 61.1% of the hEDS cohort reported recurrent infections compared to 28.5% in controls, and 72.2% had documented mast cell hypersensitivity versus 14.2% in controls. These findings provide a plausible explanation for the complex interplay between connective tissue abnormalities and immune dysregulation in hEDS. The identified genetic variants offer insights into potential therapeutic targets for modulating mast cell activity and improving patient outcomes. Future research should validate these findings in larger cohorts and explore the functional implications of these variants to develop effective treatment strategies for hEDS and related mast cell disorders.

Clustering of clinical symptoms using large language models reveals low diagnostic specificity of proposed alternatives to consensus mast cell activation syndrome criteria.

BACKGROUND: The rate of diagnosis of mast cell activation syndrome (MCAS) has increased since the disorder's original description as a mastocytosis-like phenotype. While a set of consortium MCAS criteria is well described and widely accepted, this increase occurs in the setting of a broader set of proposed alternative MCAS criteria. OBJECTIVE: Effective diagnostic criteria must minimize the range of unrelated diagnoses that can be erroneously classified as the condition of interest. We sought to determine if the symptoms associated with alternative MCAS criteria result in less concise or consistent diagnostic alternatives, reducing diagnostic specificity. METHODS: We used multiple large language models, including ChatGPT, Claude, and Gemini, to bootstrap the probabilities of diagnoses that are compatible with consortium or alternative MCAS criteria. We utilized diversity and network analyses to quantify diagnostic precision and specificity compared to control diagnostic criteria including systemic lupus erythematosus, Kawasaki disease, and migraines. RESULTS: Compared to consortium MCAS criteria, alternative MCAS criteria are associated with more variable (Shannon diversity 5.8 vs 4.6, respectively; P = .004) and less precise (mean Bray-Curtis similarity 0.07 vs 0.19, respectively; P = .004) diagnoses. The diagnosis networks derived from consortium and alternative MCAS criteria had lower between-network similarity compared to the similarity between diagnosis networks derived from 2 distinct systemic lupus erythematosus criteria (cosine similarity 0.55 vs 0.86, respectively; P = .0022). CONCLUSION: Alternative MCAS criteria are associated with a distinct set of diagnoses compared to consortium MCAS criteria and have lower diagnostic consistency. This lack of specificity is pronounced in relation to multiple control criteria, raising the concern that alternative criteria could disproportionately contribute to MCAS overdiagnosis, to the exclusion of more appropriate diagnoses.

Mast Cell Disorders and Hymenoptera Venom-Triggered Anaphylaxis: Evaluation and Management.

Patients with Hymenoptera venom allergy (HVA), especially those with severe anaphylaxis, frequently have concomitant clonal mast cell disease (MCD) in the form of systemic mastocytosis or monoclonal mast cell activation syndrome. Detection of clonal MCD is important because it will have significant consequences for managing HVA. Therefore, we recommend patients with HVA be systematically screened for clonal MCD. The pretest probability of clonal MCD can be assessed in a stepwise fashion starting with examination of the skin for typical monomorphic maculopapular cutaneous mastocytosis lesions; measurement of the baseline serum tryptase (BST) and tryptase genotyping for patients with BST greater than 11 ng/mL; followed by the Red Española de Mastocitosis score, which is calculated using anaphylaxis clinical features, BST, and the patient's sex. A bone marrow biopsy should be performed in patients with monomorphic maculopapular cutaneous mastocytosis, a Red Española de Mastocitosis score of 2 or greater, or an elevated BST based on tryptase genotype. Patients with HVA and a clonal MCD should be treated with immunotherapy directed against the Hymenoptera venom for which they are sensitized. For this high-risk subgroup of patients with HVA, it is recommended to continue immunotherapy for more than 5 years or indefinitely and to carry at least three epinephrine autoinjectors. Future studies should determine whether KIT D816V-selective tyrosine kinase inhibitors are effective at preventing or reducing the severity of Hymenoptera-venom triggered anaphylaxis in patients with clonal MCD.

The Suggested Relationships Between Common GI Symptoms and Joint Hypermobility, POTS, and MCAS.

An increasing number of reports suggest an association between a newly recognized disease cluster and significant and often disabling gastrointestinal (GI) symptoms. This cluster is composed of diagnoses of hypermobility spectrum disorders (HSDs) such as joint hypermobility and hypermobile variant Ehlers-Danlos syndrome (hEDS), postural orthostatic tachycardia syndrome (POTS), and mast cell activation syndrome (MCAS). The diagnosis of these entities remains a challenge, as the pathophysiology of each has not been completely elucidated and the diagnostic criteria continue to evolve. This article describes a cohort of young adult females who shared similar GI symptoms, with intractable nausea and vomiting being most prominent and gastroesophageal reflux disease and constipation also occurring. Most strikingly, these females also exhibited or reported a history of HSD, hEDS, POTS, and/or MCAS. The clinical course of their GI symptoms was remarkable for considerable challenges in management, and artificial nutritional support proved necessary for some. This article describes the clinical features and outcomes of their GI manifestations, examines how these manifestations might be linked to their systemic syndromes, and discusses whether a shared pathophysiology exists. Pending the definition of a common thread between these conditions, this article seeks to raise awareness of their clinical definitions and foster research that will hopefully improve outcomes for these patients.

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.

Mast cell activation syndrome: Current understanding and research needs.

Mast cell activation syndrome (MCAS) is a term applied to several clinical entities that have gained increased attention from patients and medical providers. Although several descriptive publications about MCAS exist, there are many gaps in knowledge, resulting in confusion about this clinical syndrome. Whether MCAS is a primary syndrome or exists as a constellation of symptoms in the context of known inflammatory, allergic, or clonal disorders associated with systemic mast cell activation is not well understood. More importantly, the underlying mechanisms and pathways that lead to mast cell activation in MCAS patients remain to be elucidated. Here we summarize the known literature, identify gaps in knowledge, and highlight research needs. Covered topics include contextualization of MCAS and MCAS-like endotypes and related diagnostic evaluations; mechanistic research; management of typical and refractory symptoms; and MCAS-specific education for patients and health care providers.

Imatinib and Trigger Avoidance for Mast Cell Activation Syndrome Presenting With Attacks of Abdominal Pain, Nausea, Vomiting, and Diarrhea.

The etiology for concurrent attacks of abdominal pain, nausea, vomiting, and diarrhea can be obscure. Mast cell activation syndrome is not usually considered in this differential diagnosis. A 53-year-old paint salesman suffered severe attacks of these symptoms for the 3 decades of his career. Nortriptyline, loperamide, hyoscyamine, and ondansetron failed to address his symptoms. Mast cell activation syndrome was ultimately diagnosed. Intravenous mast cell-targeted therapy reduced severity of attacks. Multiple oral mast cell-targeted treatments were ineffective, but addition of low-dose imatinib resulted in dramatic improvement. Recognition that paint-fume exposure-triggered attacks led to behavioral modifications which further reduced symptoms.

Breast Implant Illness May Be Rooted in Mast Cell Activation: A Case-Controlled Retrospective Analysis.

Objective: To investigate the possible association between breast implant illness (BII) and mast cell activation syndrome (MCAS), which often manifests increased mast cells (MCs) in assorted tissues and may explain BII symptoms. Background: Mechanisms by which implants cause BII symptoms remain unclear, but BII and MCAS symptom profiles heavily overlap, warranting investigation of potential linkage. Methods: We retrospectively analyzed 20 implant patients who underwent explantation and total capsulectomy; 15 self-reported preoperatively they had BII (subject group); 5 felt they did not [control group 1 (CG1)]. Five prophylactic mastectomy patients constituted control group 2 (CG2). Subjects and CG1 patients completed BII symptom questionnaires preoperatively and multiple points postoperatively. With CD117 staining, average and maximum mast cell counts (MCCs) in resected tissues were determined. Results: Mean BII symptom score 2 weeks postexplantation was reduced by 77% (P < 0.0001), and 85% by 9 months. Analysis suggested BII in CG1 patients, too, who improved similarly. Among CG2 patients, healthy breast tissue showed mean and maximum MCCs of 5.0/hpf and 6.9/hpf. Mean and maximum MCCs in capsules in BII patients were 11.7/hpf and 16.3/hpf, and 7.6/hpf and 13.3/hpf in CG1 patients. All intergroup comparisons were significantly different (P < 0.0001). Conclusions: MCCs in peri-implant capsules in BII patients are increased; some implanted patients appear to have unrecognized BII. Given that neoantigenic/xenobiotic exposures commonly trigger dysfunctional MCs in MCAS to heighten aberrant mediator expression driving inflammatory and other issues, further investigation of whether BII represents an implant-driven escalation of preexisting MCAS and whether an MCAS diagnosis flags risk for BII seems warranted.

Prevention of Anaphylaxis Episodes in Idiopathic Anaphylaxis by Omalizumab.

INTRODUCTION: In 15-35 percent of patients with anaphylaxis, the triggering allergen cannot be found; therefore, a diagnosis of idiopathic anaphylaxis (IA) is made. We report on the outcomes in patients with IA treated with omalizumab. METHODS: We included consequent omalizumab-treated IA adult patients treated with omalizumab 300 mg every 4 weeks. RESULTS: Out of 7 patients, 6 were female, median age 40 years with the frequency of anaphylaxis episodes from 3 in 2 years to 5 in 4 months. Baseline tryptase ranged from 1.71 to 12.0 µg/L. An increase in tryptase during anaphylaxis was documented in 6 patients. Activating KIT p.D816V variant was detected in 2 patients. One patient also had hereditary alpha-tryptasemia (HαT). The duration of omalizumab treatment was 0.5-7.5 years. None of the patients have experienced an anaphylactic reaction since the start of treatment. Mild systemic reactions were reported in 6 patients (86%). The presence of underlying cMCD had no impact on the treatment outcome. CONCLUSION: All patients in our study had complete responses to omalizumab. The presence of KIT p.D816V and HαT did not influence the response to omalizumab treatment.

Urine Mast Cell Mediators in the Evaluation and Diagnosis of Mast Cell Activation Syndrome.

PURPOSE OF REVIEW: Mast cell activation syndrome is defined by severe, episodic, and recurrent symptoms induced by mast cell mediators with objective measurement of increase in biomarkers of mast cell activation and treatment response with mast cell therapies. Increase in serum tryptase from baseline during a mast cell activation episode is currently the most accepted biomarker measurement of mast cell release. However, during symptomatic episodes, serum tryptase can be difficult to obtain as it is a venipuncture procedure. Other objective measures of mast cell activation are needed to complement serum tryptase. RECENT FINDINGS: Urine mast cell mediators can be collected at home and are non-invasive tests. There is emerging evidence for the utility of urine mast cell mediators including histamine, cysteinyl leukotrienes, and prostaglandins in the diagnosis of mast cell activation syndrome. In this review, clinically available urine mast cell mediators will be discussed including N-methylhistamine, leukotriene E4, and 2,3-dinor-11beta-prostaglandin F2 alpha. We discuss the rationale for the use of these urine mast cell mediators and examine the studies analyzing their performance for identifying mast cell activation.

Review and Updates on Systemic Mastocytosis and Related Entities.

Mast cell disorders range from benign proliferations to systemic diseases that cause anaphylaxis and other diverse symptoms to mast cell neoplasms with varied clinical outcomes. Mastocytosis is the pathologic process of the accumulation of abnormal mast cells in different organs, mostly driven by KIT mutations, and can present as cutaneous mastocytosis, systemic mastocytosis (SM), and mast cell sarcoma. The WHO 5th edition classification divides systemic mastocytosis into bone marrow mastocytosis, indolent systemic mastocytosis, smoldering systemic mastocytosis, aggressive systemic mastocytosis, systemic mastocytosis with an associated hematologic neoplasm, and mast cell leukemia. The new ICC classifies SM slightly differently. The diagnosis of SM requires the integration of bone marrow morphologic, immunophenotypic, and molecular findings, as well as clinical signs and symptoms. Moreover, understanding the wide range of clinical presentations for patients with mast cell disorders is necessary for accurate and timely diagnosis. This review provides an updated overview of mast cell disorders, with a special emphasis on SM, including the latest approaches to diagnosis, prognostic stratification, and management of this rare disease.

Neuropsychiatric Manifestations of Mast Cell Activation Syndrome and Response to Mast-Cell-Directed Treatment: A Case Series.

Mast cell activation syndrome (MCAS) is an immune disease with an estimated prevalence of 17%. Mast cell chemical mediators lead to heterogeneous multisystemic inflammatory and allergic manifestations. This syndrome is associated with various neurologic and psychiatric disorders, including headache, dysautonomia, depression, generalized anxiety disorder, and many others. Although MCAS is common, it is rarely recognized, and thus, patients can suffer for decades. The syndrome is caused by aberrant mast cell reactivity due to the mutation of the controller gene. A case series is presented herein including eight patients with significant neuropsychiatric disorders that were often refractory to standard medical therapeutics. Five patients had depression, five had generalized anxiety disorder, and four had panic disorder. Other psychiatric disorders included attention-deficit hyperactivity disorder, obsessive compulsive disorder, phobias, and bipolar disorder. All eight patients were subsequently diagnosed with mast cell activation syndrome; six had comorbid autonomic disorders, the most common being postural orthostatic tachycardia syndrome; and four had hypermobile Ehlers-Danlos syndrome. All patients experienced significant improvements regarding neuropsychiatric and multisystemic symptoms after mast-cell-directed therapy. In neuropsychiatric patients who have systemic symptoms and syndromes, it is important to consider the presence of an underlying or comorbid MCAS.

Chemical Intolerance and Mast Cell Activation: A Suspicious Synchronicity.

Background: Chemical Intolerance (CI) is characterized by intolerances for chemicals, foods, and drugs with multi-system symptoms. As yet, the biomechanism remains unclear. One study reported converging lines of evidence supporting a substantive association between mast cell activation syndrome (MCAS) and CI. The purpose of this study is to (1) confirm a previous report demonstrating that 60% of MCAS patients report CI and (2) examine the parallels between symptoms and intolerances in CI and MCAS. Methods: Five hundred forty-four MCAS patients were assigned a clinical MCAS score using a validated assessment instrument and were assessed for CI using the validated Quick Environmental Exposure Sensitivity Index. Results: Our outcomes confirm the previously published study where the majority of MCAS patients also have CI. There was a clear overlap between various ICD-10 diagnostic categories and CI symptoms, providing further support for a potential shared mechanism. Conclusions: Exposures to pesticides, volatile organic compounds, combustion products, and mold have previously been reported as initiators of CI. However, until recently, little was known about the biological mechanism involved that could explain the multisystem symptoms associated with CI. This paper addresses a newly identified biomechanism for disease, which may underlie a host of "medically unexplained symptoms" triggered by xenobiotics.

Safety of COVID-19 mRNA vaccination and effects of SARS-CoV-2 infection in children and adults with mast cell disorders.

Mastocytosis is characterized by abnormal clonal mast cell proliferation. Given the paucity of data in patients with mastocytosis, it is crucial to assess the safety of COVID-19 vaccines in this population. We aimed to assess the risk of allergic reactions and the effect of COVID-19 infection among patients with mastocytosis. Participants were recruited from Canada and Israel between December 2021 and May 2022. Consenting participants were administered standardized questionnaires querying whether they were infected with COVID-19, if they received the first and second dose vaccines, and post-vaccination side effects including allergic reactions (urticaria/angioedema, current rash flaring, need for updosing medications, or respiratory symptoms) and common side effects including injection site reaction (ISR) and flu-like symptoms. Forty participants with mastocytosis were administered a standardized questionnaire (median age = 9, 59% male). Amongst all participants, 16 (39%) reported COVID-19 infection and most (75%) reported flu-like symptoms, 3 (19%) were asymptomatic, 1 suffered from shortness of breath/chest pain and 1 from facial flushing. Of the 25 participants who were eligible for vaccination (≥ 5 years old), 80% received a first-dose vaccine and 68% received a second-dose vaccine. Of those who received the first-dose vaccine, most (60%) remained asymptomatic, 20% developed flu-like symptoms, 20% had an ISR, and 1 patient had an allergic reaction (urticaria and swelling). Of those who received the second-dose vaccine, most (53%) were asymptomatic, and 1 had an allergic reaction. No significant difference was found between side effects of both vaccine doses. No reactions fulfilled the criteria for anaphylaxis in either dose. This study reveals that among patients with mastocytosis, COVID-19 vaccine and infection were well-tolerated in the majority of cases.

Prognostic factors for the long term outcome after surgical celiac artery decompression in MALS.

BACKGROUND: The median arcuate ligament syndrome (MALS) is a rare disease caused by compression of the celiac artery (ORPHA: 293208). Surgical treatment of MALS aims to restore normal celiac blood flow by laparoscopic celiac artery decompression. However, surgical success rates vary widely between patients, therefore adequate selection of patients is essential to improve surgical outcome. Symptoms of MALS might also overlap with other chronic multi-system disorders such as mast cell activation syndrome (MCAS). So far, no clinical or radiological parameter was found to be predictive of the postoperative outcome. We, therefore, aim to study preclinical parameters in one of the largest MALS cohorts with the focus to identify patients that would benefit from surgical MAL release. RESULTS: By analyzing 20 MALS patients that underwent surgical celiac artery decompression, we found 60% of patients (12/20) had a postoperative relief of their symptoms and a simultaneous decrease of analgetic use. No demographic, radiologic or operative parameter was able to predict postoperative symptom relief. However, mast cell activation syndrome correlated significantly (p = 0.04) with persistent symptoms after the operation. CONCLUSIONS: Overall, laparoscopic MAL release can provide immediate symptomatic relief. Despite the missing predictive value of demographic and imaging data, our data show a correlation between persistent symptoms and a co-existing mast cell activation syndrome. This suggests that MCAS symptoms might be interpreted as MALS symptoms in the presence of celiac artery stenosis and therefore surgical treatment should be evaluated carefully. Overall, the selection of patients who are most likely to respond to surgical MAL release may best be accomplished by an interdisciplinary team of gastroenterologists, radiologists and surgeons.

Mast Cell Disorders of the Gastrointestinal Tract: Clarity out of Chaos.

Pathologists are increasingly asked to evaluate mast cell infiltrates in the gastrointestinal tract when there is clinical concern for systemic mastocytosis or a variety of functional disorders, including irritable bowel syndrome and mast cell activation syndrome. Neoplastic mast cells have established quantitative, morphologic, and immunohistochemical features that facilitate their identification in gastrointestinal mucosal biopsies. Specific qualitative and quantitative findings are lacking for inflammatory mast cell-mediated disorders. This review covers histopathologic features of mast cell disorders that affect the gastrointestinal tract and offers practical guidance for their assessment in mucosal biopsies.

Dysautonomia, Hypermobility Spectrum Disorders and Mast Cell Activation Syndrome as Migraine Comorbidities.

PURPOSE OF REVIEW: Dysautonomia refers to the dysfunction of the autonomic nervous system and encompasses a wide variety of autonomic symptoms and disorders. The most common autonomic disorders are postural orthostatic tachycardia syndrome (POTS), neurocardiogenic syncope (NCS), and orthostatic hypotension (OH), which may be encountered in clinical practice as part of a triad of dysautonomia, hypermobility spectrum disorders (HSD), and mast cell activation syndrome (MCAS). Migraine is one of the most common comorbidities of POTS, HSD, and MCAS; conversely, these conditions are also prevalent in patients with migraine, especially in those with multiple systemic symptoms, such as chronic dizziness, lightheadedness, orthostatic intolerance, joint pain, and allergic symptoms. Diagnostic criteria, pathophysiologic mechanisms, and therapeutic considerations in patients with migraine and comorbid dysautonomia, HSD, and MCAS are reviewed. RECENT FINDINGS: Numerous studies indicate a significant overlap and shared pathophysiology in migraine, dysautonomia, HSD, and MCAS. In clinical setting, dysautonomia, HSD, and MCAS may present a diagnostic and therapeutic challenge in patients with migraine and require a high index of suspicion on the part of the neurologist. Diagnosis and treatment of these complex disorders in patients with migraine is essential to comprehensive patient-centric care, reduced symptom burden, and improved functional impairment secondary to both migraine and comorbidities.

Childbearing with Hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum Disorders: A Large International Survey of Outcomes and Complications.

One in 20 births could be affected by hypermobile Ehlers-Danlos syndrome or Hypermobility Spectrum Disorders (hEDS/HSD); however, these are under-diagnosed and lacking research. This study aimed to examine outcomes and complications in people childbearing with hEDS/HSD. A large online international survey was completed by women with experience in childbearing and a diagnosis of hEDS/HSD (N = 947, total pregnancies = 1338). Data were collected on demographics, pregnancy and birth outcomes and complications. Participants reported pregnancies in the UK (N = 771), USA (N = 364), Australia (N = 106), Canada (N = 60), New Zealand (N = 23) and Ireland (N = 14). Incidences were higher in people with hEDS/HSD than typically found in the general population for pre-eclampsia, eclampsia, pre-term rupture of membranes, pre-term birth, antepartum haemorrhage, postpartum haemorrhage, hyperemesis gravidarum, shoulder dystocia, caesarean wound infection, postpartum psychosis, post-traumatic stress disorder, precipitate labour and being born before arrival at place of birth. This potential for increased risk related to maternal and neonatal outcomes and complications highlights the importance of diagnosis and appropriate care considerations for childbearing people with hEDS/HSD. Recommendations include updating healthcare guidance to include awareness of these possible complications and outcomes and including hEDS/HSD in initial screening questionnaires of perinatal care to ensure appropriate consultation and monitoring can take place from the start.

Treatment of idiopathic anaphylaxis with dupilumab: a case report.

BACKGROUND: Anaphylaxis is an acute, potentially life-threatening allergic reaction that typically occurs after exposure to a trigger, while idiopathic anaphylaxis (IA) occurs in the absence of a trigger. Acute management of both triggered anaphylaxis and IA relies on the use of epinephrine. In some patients with recurrent IA, glucocorticoid prophylaxis with prednisone can be effective. While there is currently no high quality evidence for the use of other prophylactic options to prevent recurrent IA, evolving data exists to support the consideration of biologics that target IgE or the Th2 pathway. CASE PRESENTATION: We present the case of a 28 year old female with no atopic or autoimmune history with recurrent episodes of IA since childhood occurring up to twice weekly. There was improvement in acute symptoms with administration of first or second generation antihistamines and/or intramuscular epinephrine. Without an identifiable trigger, she was diagnosed with IA and frequent idiopathic urticaria and omalizumab was added to her treatment regimen with improvement in symptom frequency. After being lost to follow up, she had recurrence of symptom frequency and severity without omalizumab therapy and subsequently presented to our institution. Her workup at this point was negative for food allergy, alpha gal syndrome, systemic mastocytosis, hereditary alpha tryptasemia, carcinoid syndrome, and pheochromocytoma, and she was trialed on dupilumab with near resolution of her symptom frequency over a six month time period. CONCLUSION: Recurrent IA is a diagnosis of exclusion that is associated with high morbidity. Prophylaxis remains an area of uncertainty, although prednisone has been effective in some cases. When prednisone is contraindicated or ineffective for the prevention of IA, biologic therapies that target IgE or the Th2 pathway may present a reasonable consideration. This case adds support to the suggestion that dupilumab may be a logical off-label consideration for prophylaxis of recurrent IA. The data for dupilumab in this clinical scenario is still very limited, and further research is required before any recommendation can be made.

Learned cautions regarding antibody testing in mast cell activation syndrome.

OBJECTIVES: To describe patterns observed in antibody titer trendlines in patients with mast cell activation syndrome (MCAS, a prevalent but underrecognized chronic multisystem inflammatory disorder of great clinical heterogeneity) and offer clinical lessons learned from such pattern recognition. METHODS: The available records of 104 MCAS patients drawn from the authors' practices were reviewed, including all antibody tests therein. RESULTS: All patients had positive/elevated antibodies of various sorts at various points, but for most of the antibodies which were found to be positive at least some points, the diseases classically associated with those antibodies were not present, marking such antibodies as clinically insignificant mimickers (likely consequent to inflammatory effects of MCAS on the immune system itself driving spurious/random antibody production) rather than "on-target" and pathogenic antibodies reflecting true disease warranting treatment. We also observed two distinct patterns in trendlines of the titers of the mimickers vs. the trendline pattern expected in a true case of an antibody-associated disease (AAD). CONCLUSIONS: Our observations suggest most positive antibody tests in MCAS patients represent detection of clinically insignificant mimicking antibodies. As such, to reduce incorrect diagnoses of AADs and inappropriate treatment in MCAS patients, caution is warranted in interpreting positive antibody tests in these patients. Except in clinically urgent/emergent situations, patience in determining the trendline of a positive antibody in an MCAS patient, and more carefully assessing whether the AAD is truly present, is to be preferred.