Sweet syndrome induced by FLT3 inhibitors: case report and literature review.

Background: Acute febrile neutrophilic dermatosis, also commonly referred to as Sweet syndrome, is often associated with tumors, infections, immune disorders and medications. FLT3 inhibitor-induced Sweet syndrome is a rare complication.

Methods and results: We report a patient with relapsed and refractory acute monocytic leukemia harboring high-frequency FLT3-ITD and DNMT3a mutations. The FLT3 inhibitor gilteritinib was administered for reinduction therapy after failure of chemotherapy with a combination of venetoclax, decitabine, aclarubicin, cytarabine and granulocyte colony-stimulating factor. The leukemia patient achieved remission after 1 month of treatment. However, Sweet syndrome induced by gilteritinib, which was confirmed by skin biopsy, developed during induction therapy. Similar cases of Sweet syndrome following FLT3 inhibitor therapy for acute myeloid leukemia were reviewed.

Conclusion: Attention should be given to this rare complication when FLT3 inhibitors are used for acute myeloid leukemia therapy, and appropriate treatments need to be administered in a timely manner.