Psoriasis is a chronic, immune-mediated skin disorder that is associated with increased systemic inflammation and overproduction of inflammatory cytokines. The relationship between HCV infection and psoriasis is uncertain, but presence of HCV could change the expression of inflammatory cytokines and alter how psoriasis is expressed in susceptible patients.

Researchers at Osaka City University, Osaka, Japan, report the case of an 80-year old man with untreated HCV and a 9-year history of unmanageable psoriasis, whose symptoms and signs persisted even after topical therapy was replaced with betamethasone and the vitamin D3 analogue calcipotriol. Since the patient's HCV had not previously been treated, the researchers initiated a 12-week course of oral, fixed-dose ledipasvir–sofosbuvir to address the HCV infection.

The HCV RNA level was 6.5 log10 IU/mL when treatment was initiated, but decreased rapidly after ledipasvir–sofosbuvir therapy began. HCV became undetectable on polymerase chain reaction testing by week 4, and remained undetectable for 24 weeks after therapy was completed. In addition, shortly after ledipasvir–sofosbuvir therapy began, the patient's psoriasis skin lesions started to resolve gradually, as well. The researchers believe this case is the first to show improvement of psoriasis when therapy with a direct-acting antiviral drug was initiated.