Progressive multifocal leukoencephalopathy as the presenting feature in a patient with occult low-count monoclonal B-cell lymphocytosis.

Introduction: Low Count Monoclonal B-Cell Lymphocytosis (LC-MBL) is a relatively poorly understood entity which has been suggested to be very common in asymptomatic adults and possibly related to infectious complications despite not progressing to CLL. Methods: We describe the first case of Progressive Multifocal Leukoencephalopathy (PML) presenting in a 72-year-old man with LC-MBL but no other immunocompromising conditions. Results: A diagnosis of PML was confirmed with classic MRI findings in association with a high CSF John Cunningham polyomavirus (JCV) viral load (4.09' 105 copies/mL). An extensive search for underlying immunocompromising conditions only demonstrated LC-MBL representing approximately 4% of total leukocytes (0.2' 109/L). Discussion: This is the first report of PML in association with LC-MBL. Careful review of peripheral blood flow cytometry results is necessary to identify this disorder. Further study of the epidemiology and infectious complications of LC-MBL are warranted.

Introduction: La lymphocytose monoclonale à cellules B (LMB) est une maladie relativement mal comprise qui serait très courante chez des adultes asymptomatiques et qui pourrait être liée à des complications infectieuses, même si elle n'évolue pas en leucémie lymphocytique chronique. Méthodologies: Nous décrivons le premier cas de leucoencéphalopathie multifocale progressive (LEMP) observé chez un patient (72 ans) atteint de LMB, mais ne présentant pas d'autres pathologies induisant une immunodéficience. Résultats: Des résultats d'IRM classiques et une forte charge du virus JC (John Cunningham) dans le liquide céphalorachidien (4,09 × 105 copies/mL) ont confirmé un diagnostic de LEMP. De nombreux tests visant à révéler une immunodéficience sous-jacente ont seulement montré que les cellules B monoclonales représentaient environ 4% des leucocytes totaux (0,2 × 109/L). Discussion: Il s'agit du premier cas observé de LEMP en association avec une LMB. Il faut analyser soigneusement les résultats d'une cytométrie en flux du sang périphérique pour diagnostiquer ce trouble. Il convient de continuer d'étudier l'épidémiologie et les complications infectieuses de la LMB.

Urticaria pigmentosa and systemic mastocytosis.

Key Clinical Message: Additional investigations for systemic involvement should be initiated once the diagnosis of cutaneous mastocytosis has been established in an adult patient. A serum tryptase can serve as a screening test for systemic mastocytosis, and persistent elevations should prompt further investigations, such as bone marrow studies. Abstract: Urticaria pigmentosa (UP) is the most common form of cutaneous mastocytosis, presenting as a wide variety of macroscopic appearances. Cutaneous mastocytosis in pediatric patients usually does not present with systemic involvement, but more than half of adult patients with cutaneous mastocytosis demonstrate systemic involvement. Currently, there is no guidance surrounding systemic testing in patients with UP. A 50-year-old Caucasian male was referred to the Clinical Immunology and Allergy clinic with a history of a rash. He initially presented to hospital 12 years prior with group A beta hemolytic streptococcus bacteremia treated with multiple different antibiotics. One week following discharge, he developed erythematous brown spots on his right leg which were flat, non-pruritic, and not painful. The rash later expanded to his trunk and extremities. A skin biopsy performed 2 years prior to referral to our clinic demonstrated urticaria pigmentosa. The CD117 immunohistochemical stain showed increased perivascular and interstitial mast cells in the superficial dermis. Darier's sign was negative on physical examination, and venom testing was also negative. Although he had no symptoms of systemic involvement, his serum tryptase was elevated at 47.6 ng/mL in the context of normal kidney and liver function. A skeletal survey was normal, and an abdominal ultrasound ruled out splenomegaly. Bone marrow biopsy demonstrated a mild increase in paratrabecular and perivascular atypical mast cells, in keeping with systemic mastocytosis. Adult patients with cutaneous mastocytosis have a high likelihood of having an underlying systemic mast cell disorder. Therefore, any patient presenting with characteristic skin findings should be investigated as having a cutaneous manifestation of systemic mastocytosis. This case demonstrates the utility of serum tryptase and its role in triggering additional investigations and guiding appropriate therapy.

Comparing the risk of anaphylaxis requiring epinephrine in oral immunotherapy and subcutaneous immunotherapy: A review of recent Canadian real-world literature.

Background: The safety of pediatric food oral immunotherapy (Ped-OIT) has been depicted by some as less favorable than subcutaneous immunotherapy (SCIT) owing to the increased number of serious adverse events requiring epinephrine. A review of real-world data comparing Ped-OIT and SCIT safety is necessary to guide shared decision making. Objectives: Our aim was to compare the safety and adverse event profiles of peanut Ped-OIT and SCIT using Canadian real-word literature. Methods: We performed a retrospective review of recent Canadian real-world literature on peanut Ped-OIT and SCIT safety and adverse events. Results: The incidences of systemic reactions requiring epinephrine were 11 in 270 patients (4.07%) and 12 in 41,020 doses (0.029%) in a multicenter study in British Columbia, Alberta, Manitoba, and Nova Scotia studying 270 preschool-age children treated with peanut OIT. Similarly, a multicenter study in South-Western Ontario examining 160 patients between the ages of 1 and 17 years who were treated with peanut OIT showed that the incidences of systemic reactions requiring epinephrine were 5 in 160 patients (3.1%) and 8 in 52,751 doses (0.015%). A single-center retrospective review of 380 patients receiving aeroallergen SCIT showed that the incidences of systemic reactions requiring epinephrine were 28 in 380 patients (7.4%) and 1 in 1047 injection visits (0.095%). These findings are comparable to those of a review of 860 patients in Ontario who received either aeroallergen or venom SCIT, in which the incidence of systemic reaction requiring epinephrine was 10 in 4242 injections (0.24%). Conclusion: Despite differences in the OIT protocols used and age groups studied, recent real-world data suggest that the safety of preschool peanut OIT or peanut OIT using a slower buildup schedule is comparable to that of SCIT.

The Risk of Allergic Reaction to SARS-CoV-2 Vaccines and Recommended Evaluation and Management: A Systematic Review, Meta-Analysis, GRADE Assessment, and International Consensus Approach.

Concerns for anaphylaxis may hamper severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunization efforts. We convened a multidisciplinary group of international experts in anaphylaxis composed of allergy, infectious disease, emergency medicine, and front-line clinicians to systematically develop recommendations regarding SARS-CoV-2 vaccine immediate allergic reactions. Medline, EMBASE, Web of Science, the World Health Organizstion (WHO) global coronavirus database, and the gray literature (inception, March 19, 2021) were systematically searched. Paired reviewers independently selected studies addressing anaphylaxis after SARS-CoV-2 vaccination, polyethylene glycol (PEG) and polysorbate allergy, and accuracy of allergy testing for SARS-CoV-2 vaccine allergy. Random effects models synthesized the data to inform recommendations based on the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) approach, agreed upon using a modified Delphi panel. The incidence of SARS-CoV-2 vaccine anaphylaxis is 7.91 cases per million (n = 41,000,000 vaccinations; 95% confidence interval [95% CI] 4.02-15.59; 26 studies, moderate certainty), the incidence of 0.15 cases per million patient-years (95% CI 0.11-0.2), and the sensitivity for PEG skin testing is poor, although specificity is high (15 studies, very low certainty). We recommend vaccination over either no vaccination or performing SARS-CoV-2 vaccine/excipient screening allergy testing for individuals without history of a severe allergic reaction to the SARS-CoV-2 vaccine/excipient, and a shared decision-making paradigm in consultation with an allergy specialist for individuals with a history of a severe allergic reaction to the SARS-CoV-2 vaccine/excipient. We recommend further research to clarify SARS-CoV-2 vaccine/vaccine excipient testing utility in individuals potentially allergic to SARS-CoV2 vaccines or their excipients.

A single centre retrospective study of systemic reactions to subcutaneous immunotherapy.

BACKGROUND: Subcutaneous immunotherapy (SCIT) is the standard approach for treating patients with sensitizations to aeroallergens. However, immunotherapy can trigger severe systemic reactions if delivered inappropriately or to high risk patients. We sought to characterize and quantify SCIT systemic reactions requiring epinephrine administration during a 6-year period in a Canadian setting following the recommendations for components and dosages published in the 2010 Canadian Society of Allergy and Clinical Immunology (CSACI) Immunotherapy Manual. METHODS: A single centre retrospective chart review was performed for all patients with systemic reactions to subcutaneous immunotherapy requiring intramuscular epinephrine injection between January 2011 and October 2017. Each systemic reaction requiring epinephrine was reviewed for baseline patient characteristics, details of the reaction, and reaction severity. Research ethics approval was obtained through McMaster University. RESULTS: 28 of 380 patients experienced a systemic reaction requiring epinephrine administration, with an incidence rate of 1 per 1,047 injection visits (0.095%). 26 of the 28 reactions occurred within the mandatory 30-minute observation period post allergen immunotherapy. Of the 28 patients that experienced a systemic reaction to SCIT, 11 patients had asthma and 5 patients had a history of possible food allergy. All of the systemic reactions occurred during injections from vial number 4, and five patients reacted to their first shot of a re-ordered extract. 10 of the 28 patients required more than one intramuscular injection of epinephrine, and 20 of 28 patients were transferred to the hospital by ambulance. CONCLUSIONS: This is the first Canadian study to review patients with systemic reactions to subcutaneous immunotherapy. Several best practice methods were employed throughout the study to optimize subcutaneous delivery of immunotherapy extract, and our recorded per injection incidence rate for systemic reactions was comparable or below the rate published in similar studies. The recommendations in the CSACI Immunotherapy Manual provide an approach to standardizing prescriptions for SCIT to maximize immunotherapy efficacy and reduce the risk of systemic reactions, though similar studies in larger multicenter settings are needed to confirm these observations. These observations provide important objective information to clinicians about the potential risks for systemic reactions in patients considering SCIT.

New onset colitis in an adult patient with chronic granulomatous disease treated with hematopoietic stem cell transplantation: a diagnostic dilemma.

BACKGROUND: Chronic granulomatous disease (CGD) is a rare primary immunodeficiency characterized by recurrent life-threatening bacterial and fungal infections, granuloma formation and intestinal disease. This disease is caused by defects in NADPH oxidase, which result in the inability of phagocytes (neutrophils, monocytes and macrophages) to destroy certain microbes. The only established curative therapy for CGD is hematopoietic stem cell transplantation. CASE PRESENTATION: A 23-year-old Caucasian male with X-linked chronic granulomatous disease underwent a reduced-intensity conditioning, matched unrelated donor peripheral blood stem cell transplant, after which he was started on tacrolimus and mycophenolate for graft-versus-host disease prophylaxis. Seven months later, he was admitted to hospital for nutritional support secondary to odynophagia and anorexia. Upper endoscopy revealed ulcers in his esophagus, and he was initially treated with acyclovir due to the risk of CMV infection until biopsies came back negative for viral colitis. Following a sigmoidoscopy that showed nonspecific colitis, he was started on mesalamine. Although pathology showed a pattern of widespread inflammatory changes initially suggestive of CGD colitis, a peripheral blood chimerism study showed 100% donor alleles suggesting CGD remission. Since this patient's colitis was refractory to other immunomodulators, and due to its severity, the patient underwent a partial colectomy 1 year after his HSCT and will likely require the removal of the remaining large bowel. CONCLUSIONS: This case demonstrates a unique presentation of colitis in a post-transplant CGD patient. Since CGD colitis could be excluded due to the patient's recent successful hematopoietic stem cell transplantation, a broad differential diagnosis is required for determining the etiology of this new-onset colitis in this patient with pre-existing chronic granulomatous disease. This case delineates the need for interdisciplinary care and describes a severe case of colitis after hematopoietic stem cell transplantation.