61-year-old woman. She was in remission for ulcerative colitis with mesalazine, azathioprine and infliximab treatment. Psoriasiform dermatitis developed 3 years after the administration of infliximab, and it was diagnosed as a paradoxical reaction due to anti-TNF-α antibody therapy. After switching from infliximab to vedolizumab, psoriasiform dermatitis was markedly improved. In the treatment of intractable psoriasiform dermatitis, changing to a molecular target agent with a different mechanism of action could be considered as one of therapeutic options.
