Paradoxical psoriasis induced by tumor necrosis factor alpha antagonists is a rare side effect of those drugs and has similarities with and differences from classical psoriasis in clinical and pathological characteristics. Treating severe paradoxical psoriasis is challenging because the reported cases are rare, with treatment experience being only anecdotal.
We report 2 cases of paradoxical psoriasis caused by infliximab. Both cases manifested with a significant number of pustular lesions and had protracted and complicated clinical courses. In case 1, secukinumab alone could not control the eruptions, but colchicine supplementation markedly decreased disease activity. In case 2 miscellaneous medications were administered, including the systemic drug acitretin, the immunosuppressive drug cyclosporine, and the biologic agent ustekinumab. However, multiple applications of those medications failed to prevent new lesions from occurring. Both cases showed moderate-to-high anti-nuclear antibody titers.
Based on these cases, moderate-to-high anti-nuclear antibody titer seems to be a risk factor for paradoxical psoriasis. In addition, extensive pustular presentation may be a negative prognostic indicator and may portend a protracted clinical course refractory to therapy.