[CD30-positive anaplastic large cell T-cell lymphoma developing during immunosuppressive therapy of pityriasis rubra pilaris with ustekinumab].

The development of malignancies during therapy with biologics has been discussed controversially. A patient with extensive pityriasis rubra pilaris failed to respond to standard therapeutic approaches. While receiving immunomodulatory therapy, lastly with ustekinumab, the patient developed a CD30(+) anaplastic large cell lymphoma.