Linear Psoriasis along Blaschko's Lines

106 Ann Dermatol Received October 27, 2015, Revised December 11, 2015, Accepted for publication December 18, 2015 Corresponding author: You Chan Kim, Department of Dermatology, Ajou University School of Medicine, 164 WorldCup-ro, Yeongtong-gu, Suwon 16499, Korea. Tel: 82-31-219-5190, Fax: 82-31-219-5189, E-mail: [email protected] This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright © The Korean Dermatological Association and The Korean Society for Investigative Dermatology however, patch testing is the most sensitive diagnostic test but is not specific for gold. In fact, gold cross-react with mercury in both humans and experimental animals, a cross-reaction is likely to be the cause of about 10%∼ 20% of the reactions reported to gold (Nakada et al. and our unpublished study). For quantitative analysis, atomic electronic structures of gold and mercury are very similar and very close in the periodic table, leading to an atomic mimicry by cross-reactivity between mercury and gold. Of note, mercury has atomic number 80 and gold, with the slightly less atomic number (Z=79), do share their electrons giving stable metallic bond. Likewise, in type III hypersensitivity reactions (or Arthus-type reactions), it is interesting to note that both gold and mercury may induce pathological processes mediated by circulating immune complexes. It may therefore be worth considering this possibility when examining patients with contact allergy to gold and cross-reactions between gold and mercury should not be forgotten. REFERENCES