Clinical relevance of positive patch test reactions to lanolin: A ROAT study

Sensitization to Lanolin in North-Eastern Italy, 1997-2021: Prevalence, Risk Factors and the Impact of Occupation

Background: Direct skin contact with items containing lanolin can induce sensitization and development of contact dermatitis (CD). This multi-centric study investigated prevalence of lanolin sensitization among 30,269 outpatients from North-Eastern Italy patch tested during 1997-2021. Methods: European baseline and extended Triveneto series were applied on the upper part of patients' back and removed after 48 h. Risk factors for lanolin sensitization were investigated by multiple logistic regression analysis, reporting adjusted odds ratios (aOR) with 95% confidence interval (95%CI). Results. Overall lanolin patch test positive ratio (PTPR) was 1.64% (=501/30,629), with variability over time and by research center. The body area most frequently affected by CD were hands (36.32%), followed by face (19.52%) and legs (8.09%), with a lanolin PTPR of 1.68%, 1.37% and 3.07%, respectively. Prevalence of occupational CD was 8.24%, and 1.83% patients with occupational CD patch tested positive against lanolin. Lanolin sensitization was significantly higher in males (aOR = 1.34; 95%CI: 1.08; 1.65) and among patients with leg CD aged 49-60 years (aOR = 2.34; 95%CI: 1.20; 4.57) or older than 60 (aOR = 4.21; 95%CI: 2.59; 6.85). Sub-group analysis confirmed the significantly higher sensitization rate of older patients with leg CD, with much stronger effect size in females 61+ years old (aOR = 5.33; 95%CI 2.87; 9.89) than males in the same age group (aOR = 2.92; 95%CI: 1.34; 6.39). Moreover, female house painters were more likely to test positive to lanolin. Conclusions: The variability of lanolin PTPR over time and by research center endorsed the ongoing debate on the relevance of the respective skin reaction. Clinicians assessing patients with dermatitis should collect information on potential risk factors for lanolin sensitization, particularly use of skin care products containing the hapten. Occupational exposure to lanolin-containing varnishes should also be considered.

Allergic Contact Dermatitis to Linalool Hydroperoxides: Pitfalls in the Diagnostic Process-Findings from a Repeated Open Application Test Study

Background: Increasing trends of oxidized linalool contact allergy have been reported. However, the impact of reactivity and dose in eliciting allergic contact Dermatitis caused by linalool hydroperoxides is insufficiently investigated. Objectives: To perform repeated open application tests (ROATs) using the real-world concentrations of linalool hydroperoxides in patients and control participants. Materials and Methods: Patients who previously had a positive (patients) and a negative (controls) patch test reaction to linalool hydroperoxides 1.0% in petrolatum were patch tested with a dilution series of linalool hydroperoxides preparations and asked to perform ROAT twice daily with 3 concentrations of linalool hydroperoxides creams and a negative control cream for 28 days. The creams contain 44, 140, and 440 PPM of linalool hydroperoxides, representing real-world doses reported in consumer products. Results: Of all 47 participants, 31 were linalool hydroperoxides contact allergy patients, and 16 were controls. One patient had a positive ROAT reaction in the area where cream at the highest concentration of linalool hydroperoxides was applied for 28 days. Conclusions: Repeated exposure to creams containing linalool hydroperoxides at real-life concentrations could rarely elicit an allergic reaction on intact skin after 4 weeks.

Lanolin

Lanolin is a complex mixture of high molecular weight esters, aliphatic alcohols, sterols, fatty acids, and hydrocarbons that has been widely used for centuries for its emollient properties. The purification of crude lanolin into lanolin wax and the processing of this wax into various derivatives began in 1882 and continue to this day with newer highly purified anhydrous lanolins. Controversy as to lanolin's allergenicity began in the 1920s and remains an issue. The most appropriate patch test preparation(s) for detecting allergy remain disputed. Detection of lanolin-induced contact dermatitis in diseased skin by patch testing on normal skin may lead to false negative results. Patients with a positive patch test to lanolin may tolerate use of lanolin on normal skin. Although lanolin is a weak sensitizer and the frequency of contact allergy to it in the European population reportedly is 0.4%, there are high-risk concomitant conditions: stasis dermatitis, leg ulcers, perianal/genital dermatitis, and atopic dermatitis (AD). Children and the elderly are also at greater risk of developing contact allergy to lanolin, partly because of comorbidities (AD and stasis dermatitis/leg ulcers, respectively). Finally, in the United States, non-Hispanic white patients are more likely than their non-Hispanic black counterparts to be lanolin allergic.

Moisturizer in Patients with Inflammatory Skin Diseases

As interest in skin increases, the cosmetic market is also growing. It is difficult to choose between the numerous types of basic cosmetics on the market. This article aims to provide advice and guidance on which products to recommend according to a patient’s skin condition. Appropriate application of a moisturizer attempts not only to improve the dryness, but also improve the skin’s natural barrier function to protect the skin from internal and external irritants to keep the skin healthy. Moisturizers consist of various ingredients, including occlusive agents, emollients, humectants, lipid mixture, emulsifiers, and preservatives. Pathophysiology of dry skin is also discussed to provide readers with the background they need to choose the right moisturizer for themselves. As moisturizers play an important role as adjuvant in the treatment of common skin diseases, such as atopic dermatitis, contact dermatitis, psoriasis, acne and rosacea, which type of moisturizer is appropriate for each disease was also dealt with. Basic cosmetics, especially moisturizers, should be recommended in consideration of the ingredients, effectiveness and safety of each product, and the skin condition of each patient.

Clinical relevance of positive patch test reactions to lanolin: A ROAT study

Background

Lanolin is often included when patch testing for common contact allergens. The clinical relevance of a positive patch test reaction to lanolin markers is, however, still a subject for debate.

Objectives

To evaluate Amerchol L101 as a marker of lanolin allergy and investigate the clinical impact of lanolin‐containing moisturizers on healthy and damaged skin using the repeated open application test (ROAT).

Methods

Twelve test subjects and 14 controls were patch tested with Amerchol L 101 and additional lanolin markers. Subsequently, a blinded ROAT was performed on the arms of the study participants for 4 weeks. Each participant applied a lanolin‐free cream base and two different lanolin‐containing test creams twice daily on one arm with intact skin and on the other arm with irritant dermatitis, induced by sodium lauryl sulfate (SLS).

Results

Eleven test subjects (92%) had positive patch test reactions to Amerchol L 101 when retested and one test subject (8%) had a doubtful reaction. None of the study participants had any skin reactions to the ROAT on intact skin and all participants healed during the ROAT on damaged skin.

Conclusions

Lanolin‐containing emollients do not cause or worsen existing dermatitis when performing ROAT in volunteers patch test positive to Amerchol L101.