International Journal of Research in Dermatology | January-February 2020 | Vol 6 | Issue 1 Page 115 International Journal of Research in Dermatology Hirota S et al. Int J Res Dermatol. 2020 Jan;6(1):115-117 http://www.ijord.com Case Report Oral lichenoid contact reaction to amalgam occurring as a leukoplakia-like lesion: a case report Silvio Hirota, Norberto Sugaya, Dante Migliari* INTRODUCTION Oral mucosal contact reactions (OMCR) is not a very common type of oral change, although the oral mucosa is exposed on a daily basis to many potential products capable of causing some allergic reaction. 1,2 The amalgam filling, or better, its components, particularly the mercury, is the most common substance in producing OMCR. The reason is the long contact of amalgam fillings with oral surfaces, which, eventually, may trigger an oral mucosal reaction. Due to its delay nature, this process falls in the category of a type IV, cell-mediated, hypersensitivity reaction, also called delayed hypersensitivity. 3,4 Concerning the particular event of a contact reaction to amalgam, the mucosal changes are called oral lichenoid contact reactions (OLCR) due to its similarity, both clinical and histopathologically, to the idiopathic oral lichen planus. 4,5 At times, the clinical evaluation of hypersensitivity reaction poses some difficulty because lesions, very often, do not follow a specific clinical pattern. It helps the diagnosis when a lesion is in direct contact with amalgam restoration; otherwise, the investigation requires a very sharp mind. This report describe a case showing in the patient a combination of a contact lesion to amalgam filling and another of more subtle recognition as OLCR. CASE REPORT A 28-year-old Brazilian-African woman was referred to our oral medicine clinic for evaluation of white patches on her oral mucosa. She was not aware of these lesions until her dental surgeon had noticed them and asked her to come to our clinical facility. Oral examination showed white plaques on both buccal mucosa. At the right side, there was a clear contact of the lesion with an extensive amalgam filling. On the left side, there was also amalgam filling but not in direct contact with the lesions (Figure 1A and B). There was no sign of erythematous areas in combination with white patches. Some small areas of physiological melanin pigmentation can also be seen. On ABSTRACT This article reports a case of oral lichenoid contact reaction (OLCR) in which a bilateral lesion involving the buccal mucosa was observed. Its relevance lies on that the lesions could be misdiagnosed as an oral leukoplakia, since they showed a typical feature of a homogeneous white plaque; however, fortunately, this misjudgement was spared because one of the lesions, on the right-buccal side, was in direct contact with an amalgam filling. Hence, the suspicion of mucosal contact reaction was made and the patient successfully treated by amalgam replacement. Comments on diagnosing of OLCR is also included is this report. Keywords: Oral mucosal contact reaction, Hypersensitivity reaction, Oral lichenoid lesion, Diagnosis, Amalgam filling Department of Stomatology, Oral Medicine Division, School of Dentistry, University of São Paulo, Brazil Received: 10 January 2019 Revised: 15 November 2019 Accepted: 27 November 2019 *Correspondence: Dr. Dante Migliari, E-mail: damiglia@usp.br Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. DOI: http://dx.doi.org/10.18203/issn.2455-4529.IntJResDermatol20195685