Advancing the understanding of allergic contact dermatitis: from pathophysiology to novel therapeutic approaches

Allergic contact dermatitis (ACD) is a common inflammatory skin disease that, especially when the condition becomes chronic, has a high impact on the quality of life and represents a significant disease burden. ACD represents a type IV delayed-type hypersensitivity reaction that is triggered by contact with an allergen in previously sensitized individuals through the activation of allergen-specific T cells. In the acute phase, it is characterized by eczematous dermatitis, which presents with erythema, edema, vesicles, scaling, and intense itch. Non-eczematous clinical forms are also described (lichenoid, bullous, and lymphomatosis). Lichenification is the most common clinical picture in the chronic phase if the culprit allergen is not found or eliminated. ACD can be associated with both occupational and non-occupational exposure to allergens, representing approximately 90% of occupational skin disorders along with irritant contact dermatitis. Patch testing with suspected allergens is required for a diagnosis. Metals, especially nickel, fragrance mix, isothiazolinones, and para-phenylenediamine, are the most commonly positive allergens in patients patch tested for suspected ACD. The treatment goal is to avoid contact with the culprit agent and use topical and/or systemic corticosteroid therapy

Congenital Self-Healing Langerhans Cell Histiocytosis: A Rare Presentation of Blueberry Muffin Baby “Spectrum”

A case of congenital self-healing Langerhans cell histiocytosis (CSHLCH), also known as Hashimoto-Pritzker disease, is reported. The newborn presented as blueberry muffin baby at birth, showing numerous non-blanching blue-purplish and dark-red papular, nodular lesions without documented infections and systemic involvement. Histopathological and immunohistochemical findings were suggestive for Langerhans cell histiocytosis. During the first 12 weeks of life, the cutaneous lesions progressively and spontaneously regressed with some atrophic scars. One-year follow-up is negative for relapse of cutaneous lesions or systemic involvement, confirming the diagnosis of CSHLCH

Skin tests in urticaria/angioedema and flushing to Pfizer-BioNTech SARS-CoV-2 vaccine: limits of intradermal testing

Non availabl

Airborne allergic contact dermatitis caused by Machaerium scleroxylon: confirmation by in vivo and in vitro tests

Airborne agents can cause several skin reactions in occupational and less frequently in non-occupational settings, due to their strong irritant and/or sensitizing properties (1). Airborne allergic contact dermatitis is frequently caused by woods (2), above all tropical and subtropical woods containing many strong contact allergens, such as quinones (3). A case of airborne allergic contact dermatitis caused by Machaerium (M.) scleroxylon, confirmed by in vivo and in vitro tests, is described. This article is protected by copyright. All rights reserved

Airborne allergic contact dermatitis caused by Machaerium scleroxylon

Airborne agents can cause several skin reactions in occupational and less frequently in non-occupational settings, due to their strong irritant and/or sensitizing properties (1). Airborne allergic contact dermatitis is frequently caused by woods (2), above all tropical and subtropical woods containing many strong contact allergens, such as quinones (3). A case of airborne allergic contact dermatitis caused by Machaerium (M.) scleroxylon, confirmed by in vivo and in vitro tests, is described. This article is protected by copyright. All rights reserved

Contact allergy to hydroxyisohexyl 3-cyclohexene carboxaldehyde in Italy: Prevalence, trend, and concordance with fragrance mix 2

Background: Hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC), contained in fragrance mix 2 (FM2), has been recognized as a contact sensitizer since the mid-1990s. After several attempts to reduce its use during the last two decades, HICC was permanently banned from the European market in August 2021. Objectives: To assess the prevalence and the time trend of contact allergy to HICC and to investigate the concordance of HICC allergy compared to FM2 allergy in an unselected Italian patch test population. Methods/patients: Retrospective analysis on demographics and patch test results of HICC-sensitized and/or FM2-sensitized patients was performed over a 6-year period (2016-2021) at 6 patch test Clinics in Italy. Results: Among 7266 patients (4942 females, 68.0%, mean age 45.4 ± 20.6 years), 1% (70) resulted positive to HICC and 2.1% (153) to FM2. Clinical relevance was documented in 72.9% (51/70) of HICC positive patients. Among the 169 HICC and/or FM2 positive patients, 9.5% had a positive reaction to HICC only, 31.9% to both HICC and FM2, and 58.6% to FM2 only. The prevalence trend line of HICC positive reactions showed a decrease from 1.15% (2016) to 0.96% (2021). Conclusions: We documented a decreasing trend of HICC allergy in Italy, in line with the data recently reported in literature. Nevertheless, HICC should be maintained in the baseline series to monitor the benefits of its ban from the European market

Delayed hypersensitivity reactions to iodinated contrast media: A diagnostic approach by skin tests

Background: Adverse drug reactions to iodinated contrast media (ICM) have risen due to their increasing use in x-ray-based imaging modalities. Delayed hypersensitivity reactions are mainly caused by nonionic monomeric compounds and represent an issue impacting the diagnostic-therapeutic pathways of cancer, cardiology and surgery patients. Objectives: To prospectively evaluate the usefulness of skin tests in delayed hypersensitivity reactions to ICM and to evaluate the tolerability of iobitridol, a monomeric nonionic low osmolality compound, as a possible safe alternative. Methods: Patients with delayed hypersensitivity reactions to ICM referred to us from 2020 to 2022 were prospectively enrolled in the study. All patients underwent patch test and, if negative, intradermal test with the culprit ICM and iobitridol as alternative. Results: A total of 37 patients (females 24, 64.9%) were enrolled in the study. Iodixanol and iomeprol were the most frequently involved ICM (48.5% and 35.2%, respectively); 62.2% of patients presented maculopapular eruption, while 37.8% reported delayed urticaria-like rash. Skin tests resulted positive to the culprit ICM in 19 patients (51.4%), 16 to patch test and 3 to intradermal test. Skin tests with iobitridol, tested as alternative, resulted positive in 3/19 patients (15.8%). All 16 patients with negative results to iobitridol were administered this ICM and tolerated it. Conclusions: In at least half of patients, delayed-type hypersensitivity was demonstrated by skin tests, particularly by patch test. This diagnostic approach resulted simple, cost-effective and safe, not only to confirm the culprit ICM but also to identify iobitridol as feasible alternative