A case of postural urticaria in a 14-year-old girlSofianne Gabrielli, MSc1, Michelle Le, MD2, Elena Netchiporouk, MD, MSc2, Moshe Ben-Shoshan, MD, MSc11Division of Allergy, Immunology and Dermatology, Montreal Children’s Hospital, Montreal,QC, Canada.2Division of Dermatology, McGill University, Montreal, QC, Canada.Keywords: urticaria, postural urticaria, antihistamines, omalizumabTo the Editor,Chronic urticaria (CU) is defined by the presence of wheals and/or angioedema for more than six weeks1. CU is classified as spontaneous (CSU) or inducible (CIndU) urticaria, based on the ability to identify a trigger1. CIndU, which can be classified into physical and non-physical forms, is less common than CSU and can be diagnosed by provocation test. We describe the case of a 14-year-old female patient with postural urticaria induced by changing from a seating to standing position. To our knowledge, there is only one other case of postural urticaria described in a teenage boy2.A 14-year-old female patient presented with a two-year history of intermittent hives on her bilateral legs which developed 20 minutes after standing. The patient also described symptoms of tingling in her legs prior to the development of the hives. The symptoms usually resolved after a few hours. In addition, the patient reported spontaneous hives almost daily not related to an identifiable trigger. The patient was otherwise healthy and was not taking any medication. The patient’s father reported a history of urticaria in childhood which resolved, although he still rarely experiences episodes of hives.Upon examination, the patient developed prominent vasculature (livedo reticularis) and urticaria on her bilateral legs 20 minutes after changing from a seated to a standing position (Figure 1A and 1B). When seated, the patient’s blood pressure was 113/77 and her heart rate was 102. Upon standing, the patient’s blood pressure was 101/82 and her heart rate was 118. All laboratory tests, which included a complete blood count, thyroid stimulating hormone, anti-thyroid peroxidase Immunoglobulin (Ig) G, tryptase, and total IgE, were within the normal limits. The patient’s weekly Urticaria Activity Score (UAS7) in the week prior to exam was 9.Given poor response to standard doses of second-generation anti-histamines, the patient was treated with bilastine 40 mg twice daily. After one year, due to poor response to treatment, the patient was placed on 300 mg of omalizumab administered once per month. Over the period of one year, the patient did experience improvement in her spontaneous urticaria symptoms, with her UAS7 decreasing from 38 to 9 over a period of two years. However, there was no improvement in the symptoms related to change in posture.The mechanism of action of postural urticaria in this patient is unknown. It was previously hypothesized that change in venous pressure or blood flow volume from sitting to standing may induce the release of mediators such as acetylcholine that may induce hive development2.The management of postural urticaria in our patient was not clear as she did not improve with antihistamines, nor with the addition of omalizumab treatment. It possible that the patient may gain better control of her hives with other management strategies, such as a higher dose of omalizumab3 or a different biologic, such as ligelizumab4. Clinicians should be made aware of this presentation of postural urticaria given that it may reflect a more recalcitrant form of CIndU. We suggest that a provocation test consisting of standing for 10 to 20 minutes should be used to confirm the diagnosis of postural urticaria.

Background Cold urticaria (coldU) is associated with substantial morbidity and risk of fatality. Data on coldU in children are sparse. We aimed to evaluate the clinical characteristics, management, risk of associated anaphylaxis, and resolution rate of coldU in a pediatric cohort. Additionally, we sought to compare these metrics to children with chronic spontaneous urticaria (CSU). Methods We prospectively enrolled children with coldU from 2013-2021 in a cohort study at the Montreal Children’s Hospital and an affiliated allergy clinic. Data for comparison with participants with solely CSU were extracted from a previous study. Data on demographics, comorbidities, severity of presentation, management, and laboratory values were collected at study entry. Patients were contacted yearly to assess for resolution. Results Fifty-two children with cold urticaria were recruited, 51.9% were female and the median age of symptom onset was 9.5 years. Most patients were managed with second generation H1-antihistamines (sgAHs). Well-controlled disease on sgAHs was negatively associated with concomitant CSU (adjusted odds ratio (aOR)=0.69 [95%CI: 0.53, 0.92]). Elevated eosinophils were associated with cold-induced anaphylaxis (coldA) (aOR=1.38 [95%CI: 1.04, 1.83]), which occurred in 17.3% of patients. The resolution rate of coldU was 4.8 per 100 patient-years, which was lower than that of CSU (adjusted hazard ratio=0.43 [95%CI: 0.21, 0.89], P<10-2). Conclusion Pediatric coldU bears a substantial risk of anaphylaxis and a low resolution rate. Absolute eosinophil count and co-existing CSU may be useful predictive factors.

Increased prevalence of Autoimmune Diseases in Children with Chronic Spontaneous UrticariaMichelle Le, MD1, Lydia Zhang MD2, Sofianne Gabrielli MSc2, Connor Prosty BSc, MD(c)1, Laura May Miles LLM, MD(c)2, Elena Netchiporouk, MD, MSc1, Sharon Baum, MD3, Shoshana Greenberger, MD3, Luis F. Ensina, MD, MSc, PhD4, Fatemeh Jafarian, MD1, Xun Zhang, PhD5, Moshe Ben-Shoshan, MD, MSc21Division of Dermatology, McGill University, Montreal, QC, Canada2Division of Pediatric Allergy and Clinical Immunology, Department of Pediatrics, McGill University Health Centre, Montreal, QC, Canada3Department of Dermatology, Chaim Sheba Medical Center, Tel-Aviv University, Sackler School of Medicine, Tel Hashomer, Israel4Department of Pediatrics, Federal University of São Paolo, Brazil5Centre for Outcome Research and Evaluation, Research Institute of McGill University Health Centre, Montreal, QC, CanadaCorrespondence: Michelle Le, M.D., 1001 Decarie Blvd, Montréal, Québec, H4A 3J1 email: [email protected] type: LetterManuscript word count: 981References : 10Tables : 1Figures: NoneFunding sources : NoneConflicts of interest: None declaredIRB Approval Status : Reviewed and approved by McGill University Health Centre; approval 12-255GEN