Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(4):e2022199 1 Patch Testing in Patients With Alopecia Areata: A Case-series Study Eirini Kyrmanidou1, Eleni Sotiriou2, Demetrios Ioannides2, Zoi Apalla1, A Emvalomati1, Elisavet Lazaridou1 1 Second Department of Dermatology and Venereology, Aristotle University of Thessaloniki, Thessaloniki, Greece. 2 First Department of Dermatology and Venereology, Aristotle University of Thessaloniki, Thessaloniki, Greece. Key words: alopecia areata, allergic contact dermatitis, patch test, IFN-γ Citation: Kyrmanidou E, Sotiriou E, Ioannides D, Apalla Z, Emvalomati A, Lazaridou E. Patch testing in patients with alopecia areata: a case-series study. Dermatol Pract Concept. 2022;12(4):e2022199. DOI: https://doi.org/10.5826/dpc.1204a199 Accepted: January 29, 2022; Published: October 2022 Copyright: ©2022 Kyrmanidou et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding author: Eirini Kyrmanidou, MD, MSc, Second Department of Dermatology and Venereology, Aristotle University of Thessaloniki, I.Pasalidi 77, 55132 Thessaloniki, Greece. Tel: +302314047229 Email: ekyrmanidou@gmail.com Introduction Alopecia areata (AA) is a non-scarring disorder of the hair follicle and currently pathogenesis research is focused on determining the role, contribution, and interactions between each of the immune components involved. It has been pre- viously reported that fungal infection, seasonal airborne allergens, and other allergens may contribute to the com- plex autoimmune pathways of AA [1,2]. Recently, allergy to dust mite was associated with time of onset and severity of AA [3]. Thus, and in order to examine a possible contribut- ing role of allergic contact dermatitis (ACD) in patients with AA, we performed patch testing in patients diagnosed with AA in our clinic. Case presentation Thirty-one patients, 12 males and 19 females, aged 18 to 83 years, firstly diagnosed with active AA lesions (positive hair pull test) were eligible for inclusion. Patients with personal history of atopic dermatitis (AD ) and/or ACD were excluded from the study, to diminish possible bias effect. According to the International Contact Dermatitis Research Group guide- lines, the European Baseline Series S-100 patch tests con- sisting of 32 allergens were performed as per protocol, after receiving informed consent from the participants. The inter- pretation of results was conducted in two consecutive visits, after 48 and 96 hours, to determine late allergic reactions. Two patients (6.4%, 2/31) were found positive towards nickel, 1 patient (3.2%, 1/31) had a positive reaction against methylisothiazolinone and 1 patient (3.2%, 1/31) was positive against the fragrance mix. Since there was no control group, we can only report frequency of ACD in patients with AA. Conclusions The hair follicle is characterized by immune privilege, which protects it from being exposed to immune recognition, especially 2 Research Letter | Dermatol Pract Concept. 2022;12(4):e2022199 during anagen phase of hair growth. Immune privilege collapse is considered as the starting point of an immunologic cascade resulting in AA. However, it remains unclear which is the trig- gering event leading to excessive release of INF-γ in the micro- environment around the hair follicle in patients with AA. ACD is a disease with genetic predisposition that is phe- notypically expressed after the patient’s exposure to cer- tain environmental factors. INF-γ, among other cytokines, is secreted not only during the sensitization but also during the elicitation phase of ACD [4]. Furthermore, Attia et al. reported that in patients with alopecia universalis tIgE serum levels were higher than in patients with other types of AA [5]. The rate of ACD among AA patients in our series roughly conforms with the rate reported in the general population [4]. Patients with a history of AD were excluded, since those patients have shown to have higher rates of positive patch tests compared to the general population [6]. In conclusion, we could not detect a difference in the incidence of ACD in our group of patients. We acknowledge the fact that the sample size is limited, and clearly state that larger studies are needed to clarify the precise ratio and in- vestigate a potential role of ACD in the susceptibility and/or onset of the immunologic phenomena involved in AA. References 1. Rudnicka L, Lukomska M. Alternaria scalp infection in a patient with alopecia areata. Coexistence or causative relation- ship? J Dermatol Case Rep. 2012;6(4):120-124. DOI: 10.3315 /jdcr.2012.1120. PMID: 23329992. PMCID: PMC3543859. 2. Zhao Y, Zhang B, Caulloo S, Chen X, Li Y, Zhang X. Diffuse alopecia areata is associated with intense inflammatory infiltration and CD8+ T cells in hair loss regions and an increase in serum IgE level. Indian J Dermatol Venereol Leprol. 2012;78(6):709-714. DOI: 10.4103/0378-6323.102361. PMID: 23075639.. 3. Li SF, Zhang XT, Qi SL, et al. Allergy to dust mites may con- tribute to early onset and severity of alopecia areata. Clin Exp Dermatol. 2015;40(2):171-176. DOI: 10.1111/ced.12471. PMID: 25252126. 4. Brites GS, Ferreira I, Sebastião AI, et al. Allergic contact derma- titis: From pathophysiology to development of new preventive strategies. Pharmacol Res. 2020;162:105282. DOI: 10.1016/j. phrs.2020.105282. PMID: 33161140. 5. Attia EA, El Shennawy D, Sefin A. Serum Interleukin-4 and To- tal Immunoglobulin E in Nonatopic Alopecia Areata Patients and HLA-DRB1 Typing. Dermatol Res Pract. 2010;2010:503587. DOI: 10.1155/2010/503587. PMID: 20671941. PMCID: PMC2910459. 6. Milam EC, Jacob SE, Cohen DE. Contact Dermatitis in the Patient with Atopic Dermatitis. J Allergy Clin Immunol Pract. 2019;7(1): 18-26. DOI: 10.1016/j.jaip.2018.11.003. PMID: 30598176.