De novo development of psoriatic plaques in patients receiving interferon alfa for treatment of erythrodermic cutaneous T-cell lymphoma

Presumably because of its potent immunomodulatory activity, the use of interferon has led to the development of autoimmune disease in susceptible individuals. Because psoriasis is considered to be, in part, an autoimmune phenomenon, it is plausible that interferon may influence disease activity. We describe the development of psoriatic plaques in two patients without a history of this disease while they were receiving interferon alfa and extracorporeal photochemotherapy for erythrodermic cutaneous T-cell lymphoma. Paradoxically, in both patients the erythroderma resolved with subsequent de novo onset of psoriasis. This clinical sequence provides support for disparate immune mechanisms in the pathogenesis of these disorders, both of which are typified by lymphoid infiltrates. A review of the literature reveals that all forms of interferons have been associated with the exacerbation of psoriatic plaques, but that only interferon alfa has induced de novo development of psoriasis.