Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(3):e2024172 1 Does a Tattoo Protect Against Chronic Spontaneous Urticaria? An Unusual Finding Kinga Bojahr1, Agata Sztramska1, Weronika Zysk1, Agata Rolewicz1, Jan Romantowski1, Marta Chełmińska1 1 Department of Allergology, Medical University of Gdansk, Gdansk, Poland Citation: Bojahr K, Sztramska A, Zysk W, Rolewicz A, Romantowski J, Chełmińska M. Does a Tattoo Protect Against Chronic Spontaneous Urticaria? An Unusual Finding. Dermatol Pract Concept. 2024;14(3):e2024172. DOI: https://doi.org/10.5826/dpc.1403a172 Accepted: March 14, 2024; Published: July 2024 Copyright: ©2024 Bojahr 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: Kinga Bojahr, MD, Department of Allergology, Medical University of Gdansk Mariana Smoluchowskiego Street 17, 80-214 Gdańsk, Poland. Tel: +48 58 584 4300 Email: kingabojahr@gumed.edu.pl Case Presentation A 28-year-old man was diagnosed with chronic urticaria with angioedema 15 years ago. The symptoms have been present since early childhood, but he was treated ad hoc without detailed diagnostics. According to the Urticaria Ac- tivity Score scale, the patient had 5 scores during the last 24 hours since the interview. The patient has four black, deco- rative tattoos; the first of them was made 11 years ago. They all cover ~1%–5% of the body surface and are located on the right and left forearms. The patient reports that the pres- ence of tattoos had an impact on reducing the occurrence of wheals in tattooed areas; urticarial wheals appear with much less intensity compared to other places (Figure 1, A and B). Teaching Point Current scientific literature focuses on tattoo-associated cutaneous complications, however, there are limited ther- apeutic benefits related to tattoos [1,2]. Previous reports indicated a positive effect of tattoos on psoriasis, described as a tattoo-sparing phenomenon [1]. We presented the un- usual description of the possible positive effect of tattoos on urticaria. The mechanisms of the “tattoo-protection” phenomenon observed above remain hypothetical. Among the potential causes are changes in local microcirculation, modifications in immunity, and the abundance of pigments available peri-vascularly, preventing the inflammatory pro- cess [2]. Tattoos, among other types of traumas, might be the cause of regional immune dysregulation [3,4]. Our case report appears to fit the reverse Koebner reaction (Renbök phenomenon), which is the non-appearance or disappear- ance of the dermatoses at the site of injury. Caccavale et al have proposed tattoos as one of the causes responsible for the reverse Koebner reaction [4]. According to the classifi- cation proposed by Caccavale et al, the patient described above may be considered an example of locus maioris re- sistentiae, an area of skin with greater resistance to certain reactions [4]. Macrophages are the main effector cells in the patho- physiology of tattoos, phagocytose, and deposit most of the tattoo pigment [1]. Spyridonos et al suggested that 2 Image Letter | Dermatol Pract Concept. 2024;14(3):e2024172 macrophages might play an important role in “sparing phe- nomena” in psoriasis [1]. Macrophages also emerge as a cell species in the pathophysiology of urticaria, which may be a potential explanation for the occurrence of this phenomenon in urticaria as well. Further studies might not only explain this connection but may also shed new light on urticaria pathogenesis. References 1. Spyridonos P, Zampeli V, Rapti SN, Bassukas ID. A Guttate Psoriasis That Tends to Spare Three Tattoos: A Macrophage Liaison. Case Rep Dermatol Med. 2021;2021:9448636. DOI: 10.1155/2021/9448636. PMID: 34552797. PMCID: PMC8452437. 2. Pinal-Fernandez I, Solans-Laqué R. The ‘sparing phenomenon’ of purpuric rash over tattooed skin. Dermatology. 2014;228(1): 27-30. DOI: 10.1159/000356779. PMID: 24356492. 3. Caccavale S, Di Mattia D, Ruocco E. Loco-regional immune default: The immunocompromised district in human and com- parative dermatology. Clin Dermatol. 2016;34(5):654-657. DOI: 10.1016/j.clindermatol.2016.04.009. PMID: 27638447. 4. Caccavale S, Kannangara AP, Ruocco E. Categorization of and comments on isomorphic and isotopic skin reactions. Clin Dermatol. 2017;35(1):105-110. DOI: 10.1016/j.clindermatol .2015.10.011. PMID: 27938807. Figure 1. (A,B) Sparing phenomenon in the patient (A) on the right forearm and on the (B) left forearm). An area free of urticaria surrounding a tattoo can be seen (red arrows).