Clinical Oral Medicine Oral lichen planus and hepatitis C virus infection LC Figueiredo 1 , FJ Carrilho 2 , HF de Andrade Jr 3 , DA Migliari 1 1 Department of Oral Diagnosis, University of Sa Äo Paulo School of Dentistry, Sa Äo Paulo, Brazil; 2 Clinical Hepatology Branch, Department of Gastroenterology; 3 Department of Dermatology and Tropical Disease, University of Sa Äo Paulo School of Medicine, Sa Äo Paulo, Brazil OBJECTIVE: This investigation was conducted to determine the possible association between oral lichen planus (OLP) and hepatitis C virus infection (HCV) in the population of Sa Äo Paulo (Brazil). MATERIALS AND METHODS: Three groups of patients were studied: group 1 was composed of 68 patients with OLP lesions; group 2 had 126 patients with HCV infec- tion; and the control group consisted of 898 individuals seeking dental treatment at our school, used to deter- mine the prevalence of lichen planus in the general population. The prevalence of HCV in group 1 was determined and compared with that of the population of Sa Äo Paulo (Focaccia et al (1998) Brazilian J Infec Dis 2: 269), while the prevalence of OLP in group 2 was deter- mined and compared with that of the control group. RESULTS: The results showed that the frequency of HCV in OLP patients was 8.8%, signi®cantly higher than in the general population of Sa Äo Paulo, which is 1.4% (P  0.002), and the frequency of OLP in HCV patients (4.7%) was also signi®cantly higher (P  0.0003) than that of the control group (0.6%). CONCLUSION: These data suggest that, at least in Sa Äo Paulo, there is an association between OLP and HCV infection. Oral Diseases (2002) 8, 42±46 Keywords: lichen planus; oral; liver disease; hepatitis C infection Introduction Many reports have described the association of lichen planus (LP) and chronic liver disease, especially hepa- titis C virus (HCV) infection (Rebora and Rongioletti, 1984; Ayala et al, 1986; GISED, 1990; Gandolfo et al, 1994; Nagao et al, 1995; Carrozzo et al, 1996; SaÂnchez- Pe rez et al, 1996; BagaÂn et al, 1998; Mignogna et al, 1998). It appears interesting that in most of these reports the prevalent location of LP when associated with HCV is the oral mucosa. The possible etiopathogenic mech- anism that may link the two diseases remains unclear. Other studies, however, have failed to show a signi- ®cant association between LP and liver disease (Scully et al, 1985; El-Kabir et al, 1993; Cribier et al, 1994) or to detect any serological abnormalities of liver disease in oral lichen planus (OLP) patients (Ingafou et al, 1998; van der Meij and van der Waal, 2000). Why studies have contradicted one another remains an answered question. One explanation is that geographic variation in the prevalence pattern of HCV infection could account for these contradictory data (El-Kabir et al, 1993; Roy and Bagg, 1999; Lodi et al, 2000; van der Meij and van der Waal, 2000). The aim of the present investigation was to verify the possible association between OLP and HCV infection among the population of the city of SaÄo Paulo, Brazil. Materials and methods The experimental design of this study involved three main groups: group 1 consisted of OLP patients who were tested to determine their frequency of liver abnor- malities and, subsequently, to investigate the underlying liver disease in those patients with altered liver function test; group 2 consisted of HCV patients who were examined to determine their frequency of LP/OLP lesions. In group 3, people attending for dental treatment were examined for the frequency of LP/OLP lesions. HCV infection in the general population was obtained from published studies. Details of each group are provided as follows: Group 1 comprised 68 individuals (23 males and 45 females) with OLP, ®ve with concomitant skin lesions of LP, examined at oral clinics of the University of SaÄo Paulo. The mean age was 49.2 years (range, 17±77). Clinical diagnosis of OLP was con®rmed by histologic Correspondence: Dante A. Migliari, Universidade de SaÄo Paulo, Faculdade de Odontologia, Departamento de Estomatologia, Discip- lina de Semiologia, Av. Prof. Lineu Prestes, 2227, Cidade UniversitaÂ- ria, SaÄo Paulo, SP, Brazil 05508-900. Tel/fax: +55 11 3864 1372, E-mail: damiglia@fo.usp.br Received 25 April 2001; revised 14 September 2001; accepted 14 November 2001 Oral Diseases (2002) 8, 42±46 Ó 2002 Munksgaard All rights reserved 1354-523X/01 http://www.blackwellmunksgaard.com