Erythema induratum and chronic hepatitis C infection

Erythema induratum, or nodular vasculitis, was initially described as a type of cutaneous tuberculosis. Currently, it is considered a multifactorial syndrome of lobular panniculitis of unknown cause. An association between erythema induratum and hepatitis C virus (HCV) has been suggested in previous reports. We report the case of a 49-year-old male presenting with a 3-year history of itchy, painful red to violaceous cutaneous nodules and plaques on both legs that had been unresponsive to topical dermatologic treatments. Evaluation of persistent serum transaminase elevations led to a diagnosis of chronic hepatitis C with bridging liver fibrosis. A thorough evaluation to exclude mycobacterial infection was performed, and anti-tuberculosis treatment was started based on a positive QuantiFERON test. There was no improvement in the skin lesions with this treatment. The patient then received standard antiviral therapy with pegylated interferon and ribavirin for 48 weeks. Treatment produced an early virologic response with significant improvement in the skin lesions, pain and pruritus. Six months after antiviral treatment, virologic relapse occurred without recurrence of the cutaneous lesions. There appears to be an association between erythema induratum and hepatitis C infection, probably mediated by circulating immune complexes. Interestingly, lesions improve with antiviral treatment and, as shown in this case, the effect may be sustained after stopping treatment despite virologic relapse.