Bortezomib-induced Sweet's syndrome confirmed by rechallenge.

Sweet's syndrome, also known as acute febrile neutrophilic dermatosis, is characterized predominantly by fever, elevated neutrophil count, and erythematous skin lesions composed of plaques and nodules that appear on upper extremities, face, or neck. The incidence of Sweet's syndrome in the general population is unknown due to the rarity of the condition and potential lack of reporting. Bortezomib, an antineoplastic agent that is the standard of care in patients with multiple myeloma, has been reported to be associated with Sweet's syndrome. We describe a 69-year-old man who developed Sweet's syndrome during his initial course (after cycle 4) of bortezomib for treatment of multiple myeloma; he again experienced Sweet's syndrome 3.5 years later when rechallenged with bortezomib (after cycle 5) for treatment of relapsed multiple myeloma. The patient's signs, symptoms, and biopsy results were identical during both presentations of Sweet's syndrome. In both instances, the syndrome spontaneously resolved without incident and without supportive treatment with corticosteroids or antihistamines. To our knowledge, this is the first case report of a patient who developed Sweet's syndrome during an initial course of treatment with bortezomib and after rechallenge with bortezomib for relapsed disease. As proteasome inhibitors continue to be a mainstay of therapy for both treatment and salvage therapy for multiple myeloma, this case demonstrates that rechallenge with bortezomib is an option for patients who develop Sweet's syndrome.