Ibrutinib-induced Sweet syndrome.

Ibrutinib is an oral targeted drug that has been approved by the US Food and Drug Administration (FDA) for the management of chronic lymphocytic leukemia (CLL), Waldenstrom's macroglobulinemia, and previously treated chronic graft-versus-host disease. It is an irreversible selective inhibitor of Bruton's tyrosine kinase (Btk)1. We report the case of a 54-year-old male patient, diagnosed with CLL being who was with ibrutinib. He developed several erythematous and indurated plaques on the neck, face, hands, and scalp, 8 months into his treatment. Clinical features along with skin biopsy findings of a neutrophil predominant infiltrate were consistent with the diagnosis of Sweet syndrome. Upon withdrawal of the medication and application of a potent topical steroid, cutaneous lesions healed after one week. However, readministration of the medication at a lower dose was associated, with recurrence of the lesions, suggesting a temporal relationship with ibrutinib and necessitating drug discontinuation.