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1.
Introduction
Globally, there are 120–130 million individuals infected with hepatitis C virus (HCV) and 3–4 million new cases are identified each year (1). The main risk factors for getting the infection are the use of injectable drugs, the contact with contaminated instruments and blood transfusions from unscreened subjects (2). HCV, first described in 1989, is a single stranded RNA virus, that belongs to the Flavoviridae family. HCV is a significant cause of liver cirrhosis and hepatocellular carcinoma (3,4). To date, seven genotypes have been described and their prevalence present certain geographical variations. The pathogenesis of the infection involves the activation of cytotoxic T lymphocytes which during the fight against the virus lyse the infected hepatocytes and produce liver damage (5).
Mokni et al were the first to note the association between HCV and lichen planus (LP) in 1991. They reported a case of a patient who presented with an eruption consisting of violaceous papules disseminated on his arms and trunk. Laboratory findings showed elevated transaminases and further tests confirmed the diagnosis of HCV infection. A cutaneous biopsy established the diagnosis of LP (6). Three years later, the first cases of oral lichen planus (OLP) in association with HCV infection were notified. These studies were published shortly after the isolation of HCV in 1989 (7).
LP is a chronic T cell-mediated dermatosis of unknown etiology, which affects the skin, mucous membranes, hair and nails (8). One of the main histopathological features of LP is the vacuolar degeneration of the keratinocytes in the basal layer. This phenomenon is the result of the action of T helper lymphocytes, T cytotoxic lymphocytes, natural killer cells and dendritic cells that predominate in the inflammatory infiltrate. Thus, the main pathogenic mechanisms are increased apoptosis of keratinocytes and the inhibition of apoptosis of T lymphocytes (9–11). The trigger factors remain unknown. LP is associated with certain pathological conditions such as autoimmune diseases, malignancies, stress and viral infections, of which the most notable is HCV infection (9,12).
In the following sections we present the main studies regarding the relationship between LP and HCV.
2.HCV infection and cutaneous manifestations
Numerous studies have shown that a great number of patients with chronic hepatitis C (40–75%) present extrahepatic manifestations (13). Cacoub et al...