Bullous sweet syndrome in a patient with t(9;22)(q34;q11)-positive chronic myeloid leukemia treated with the tyrosine kinase inhibitor nilotinib: interphase cytogenetic detection of BCR-ABL- positive lesional cells.

Background: An association of Sweet syndrome with chronic myeloid leukemia (CML) has been recently observed in patients treated with tyrosine kinase inhibitors.

Observations: We describe a 67-year-old patient with a 6-year history of Philadelphia chromosome translocation t(9;22)(q34;q11)-positive CML. The tyrosine kinase inhibitor AMN107 (nilotinib) kept the patient in chronic phase. After 10 months of taking nilotinib, he developed pneumonia with septic features. Seven days later, bullous skin infiltrations on the upper arms and a large, painful bullous swelling of the right neck occurred without any evidence of a viral, bacterial, or fungal blood infection. Findings from histologic examination showed massive infiltrations of the whole dermis with neutrophil granulocytes as well as with monocytoid histiocytic cells. Fluorescence in situ hybridization analysis of paraffin-embedded tissue revealed a BCR-ABL fusion, indicating the presence of t(9;22)(q34;q11). The addition of oral prednisolone to an adequate antibiotic treatment led to rapid resolution of the cutaneous infiltrations.

Conclusions: Skin infiltrations consistent with Sweet syndrome can occur in patients with septic CML during the treatment with tyrosine kinase inhibitors, including nilotinib. Skin infiltrations can include specific CML cells.