Excipients in Oral Antihistamines Can Perpetuate Allergic Contact Dermatitis

Comorbid Scenarios in Contact Dermatitis: Atopic Dermatitis, Irritant Dermatitis, and Extremes of Age

Contact dermatitis (allergic and irritant) occurs when the skin encounters haptens that elicit a T cell-mediated hypersensitivity reaction (allergic) or a nonimmunologic, toxic reaction (irritant). Patch testing is the reference standard for diagnosing allergic contact dermatitis (ACD), although positive results are not always relevant. Therefore, the definitive diagnosis of ACD requires an astute clinician able to connect the results of patch testing appropriately with the clinical history and the cutaneous examination findings. Comorbid conditions such as atopic dermatitis can confound the accurate diagnosis of ACD because of the similarities in clinical presentation. Furthermore, both extremes of age can further challenge the diagnostic specificity of ACD owing to the maturing immune system and the space limitations present when the very young are patch tested. The goal of this Continuing Medical Education article is to discuss the challenges of diagnosing ACD in patients with unique comorbidities such as atopic dermatitis, given the morphologic similarities, and when to patch test these patients. Diagnosis of ACD will also be discussed in very young patients with a focus on patch test allergen selection despite the limited geographic space. The most common allergens reported in very young and old patients will also be discussed.

Allergic contact dermatitis from propylene glycol: A case series from Australia

BACKGROUND

Propylene glycol (PG) is used in a variety of cosmetics, food and pharmaceuticals. PG is a known sensitizer but also irritating when patch tested (PT).

OBJECTIVES

The aims were to investigate the frequency of contact sensitization to PG and to identify cases of allergic contact dermatitis (ACD).

METHODS

A retrospective study was performed on patients PT at the Skin Health Institute (SHI), Victoria, Australia to PG 5% pet. and PG 10% aq. between 1 January 2005 and 31 December 2020.

RESULTS

In all, 6761 patients were PT to PG and 21 (0.31%) reacted. Of those 21 individuals, 9 (42.9%) had a relevant reaction. 75% of relevant positive reactions were in patients PT to PG 10% aq. The most common source of PG exposure was topical medicaments (77.8% of relevant reactions) and moisturizers, with the largest group being topical corticosteroids.

CONCLUSION

Contact sensitization to PG in the patch test population remains uncommon, although it is possible that testing with concentrations of 5%-10% PG did not identify all reactions. Topical corticosteroids were the most important cause. Patients with suspected contact dermatitis to topical corticosteroids should be PT to PG.

Hidden Dangers: Recognizing Excipients as Potential Causes of Drug and Vaccine Hypersensitivity Reactions

Excipients are necessary as a support to the active ingredients in drugs, vaccines, and other products, and they contribute to their stability, preservation, pharmacokinetics, bioavailability, appearance, and acceptability. For both drugs and vaccines, these are rare reactions; however, for vaccines, they are the primary cause of immediate hypersensitivity. Suspicion for these "hidden dangers" should be high, in particular, when anaphylaxis has occurred in association with multiple chemically distinct drugs. Common excipients implicated include gelatin, carboxymethylcellulose, polyethylene glycols, and products related to polyethylene glycols in immediate hypersensitivity reactions and propylene glycol in delayed hypersensitivity reactions. Complete evaluation of a suspected excipient reaction requires detailed information from the product monograph and package insert to identify all ingredients that are present and to understand the function and structure for these chemicals. This knowledge helps develop a management plan that may include allergy testing to identify the implicated component and to give patients detailed information for future avoidance of relevant foods, drugs, and vaccines. Excipient reactions should be particularly considered for specific classes of drugs where they have been commonly found to be the culprit (eg, corticosteroids, injectable hormones, immunotherapies, monoclonal antibodies, and vaccines). We provide a review of the evidence-based literature outlining epidemiology and mechanisms of excipient reactions and provide strategies for heightened recognition and allergy testing.

Pediatric allergic contact dermatitis. Part I: Clinical features and common contact allergens in children

Allergic contact dermatitis (ACD), a delayed hypersensitivity skin reaction to environmental allergens, has a prevalence that is similar in children and adults. However, diagnostic testing for ACD in pediatric populations accounts for less than one tenth of all patch tests. The relative infrequency of pediatric patch testing may be attributed to the difficulty in testing in this population, which includes a smaller surface area for patch test placement and maintaining cooperation during patch testing, especially in younger children. Diagnosis can be difficult in children because the appearance of ACD can mimic other common pediatric skin conditions, particularly atopic dermatitis and irritant contact dermatitis. Comprehensive history taking, guided by patient presentation, age group, and location of dermatitis, helps build clinical suspicion. Such clinical suspicion is one of the major reasons behind patch testing, with additional indications being recalcitrant dermatitis and dermatitis with atypical distribution. US pediatric data have shown the top allergens to be metals, fragrances, topical antibiotics, preservatives, and emollients. These trends are important to recognize to guide management and accurate diagnosis, because ACD tends to persist if the allergen is not identified and can affect patients' quality of life.

Pediatric contact dermatitis: what's new

PURPOSE OF REVIEW

Allergic contact dermatitis (ACD) was once thought to be rare in children but recent studies have demonstrated that the prevalence of ACD is common and appears to be increasing in children. Current trends including toys, hobbies, and personal care products may play a role in potentially new allergen exposure or resurgence of certain allergens, making ACD a moving target in children.

RECENT FINDINGS

ACD and atopic dermatitis can coexist and certain clinical features can help differentiate ACD from endogenous atopic dermatitis in children. It is important to consider ACD in children with recalcitrant atopic dermatitis or dermatitis with atypical distribution. Patch testing has become a more common practice in children. In 2018, the first expert consensus-derived pediatric baseline series consisting of 38 allergens was proposed to aid in the diagnosis of ACD in children. Comparing recent patch testing data in the pediatric population, the top allergens ubiquitously identified were nickel, cobalt, neomycin, Myroxylon pereirae (balsam of Peru), fragrance mix I, fragrance mix II, methylisothiazolinone, methylchloroisothiazolinone/ methylisothiazolinone, formaldehyde, and lanolin.

SUMMARY

ACD is a common problem in children. Detection through patch testing, avoidance of offending allergens, and prevention of common allergens are the main focus of management of ACD in children.