Relevance of patch testing in patients of chronic spontaneous urticaria and its correlation with serum IgE level

Objectives: Chronic spontaneous urticaria (CSU) is defined as short lived (< 24h) wheals occurring spontaneously without any triggering factors, daily or almost daily for at least 6 weeks. Though CSU is mainly a Type 1 hypersensitivity reaction, earlier studies suggested contact allergy may have some role to play an important role in the etiopathogenesis of CSU. The objective of the study is to find out the relevance of patch test in the etiopathogenesis of and its correlation with serum IgE level. Materials and Methods: Thirty-one patients of CSU were thoroughly evaluated for clinical and laboratory parameters. We conducted patch testing with Indian Standard Series (ISS) in all of them and tried to find out the relevance of every positive reaction. Relevant positive cases were asked to avoid exposure for 2 months and were maintained only in breakthrough antihistamines. Furthermore, correlation of positive patch test reaction with high IgE and eosinophil count were studied. Results: Seventeen (55%) cases came positive for patch test. Potassium dichromate, lanolin, benzocaine, and fragrance mix were the most common offenders. Patients with very high IgE count had patch test positivity with multiple allergens. Seven of the fifteen patients who had relevant positive patch results could be followed up to remission; three were lost to follow-up. Conclusion: Patch test with ISS may give important clue to in a subset of patients of CSU and thus may be considered an important part of routine investigations of CSU.

Delayed allergic skin reactions to vaccines

Background: Recent advances in vaccination against the severe acute respiratory syndrome coronavirus 2 pandemic have brought allergists and dermatologists to the forefront because both immediate and delayed hypersensitivity reactions have been reported. Objective: This literature review focused on delayed reactions to vaccines, including possible causative agents and practical information on how to diagnose, evaluate with patch testing, and manage subsequent dose administration. Methods: Currently published reviews and case reports in PubMed, along with data on vaccines from the Centers for Disease Control and Prevention web site. Relevant case reports and reviews that focused on delayed reactions to vaccines were selected. Results: Most delayed hypersensitivity reactions to vaccines include cutaneous manifestations, which vary from local persistent pruritic nodules to systemic rashes. The onset is usually within a few days but can be delayed by weeks. Multiple excipients have been identified that have been implicated in delayed vaccine reactions, including thimerosal, formaldehyde, aluminum, antibiotics, and gelatin. Treatment with antihistamines, topical corticosteroids, or systemic corticosteroids alleviates symptoms in most patients. Such reactions are generally not contraindications to future vaccination. However, for more-severe reactions, patch testing for causative agents can be used to aid in diagnosis and approach further vaccination. Conclusion: Delayed-type hypersensitivity reactions to vaccines are not uncommon. If needed, patch testing can be used to confirm agents, including antibiotics, formaldehyde, thimerosal, and aluminum. In most cases, delayed cutaneous reactions are not contraindications to further vaccine administration.

Contact Dermatitis in Nail Cosmetics

Many ingredients found within nail cosmetic products are capable of sensitizing patients’ immune systems and causing contact dermatitis (CD). These include but are not limited to tosylamide, (meth)acrylates, and formaldehyde. A clear temporal relationship between nail cosmetic procedures and an eczematous outbreak on the hands, face, or other ectopic body regions can be a key indicator of CD secondary to nail cosmetic exposure. Once an inciting allergen is identified through patch testing, elimination and avoidance becomes a mainstay of treatment alongside the use of emollients and topical anti-inflammatory therapies. Patients should be counselled to approach future nail cosmetic products and procedures with caution and careful attention to ingredients, regardless of whether or not it has a “hypoallergenic” label.