Background Ifosfamide is an alkylating agent used in the treatment of a wide range of tumours. Because of known side effects it is usually administered in combination with mesna, a thiol agent with uroprotective activity, to reduce them and increase the therapeutic dose. The most frequently administered regimens for ifosfamide are fractionated doses for 3 to 5 days, high-dose intravenous bolus, and continuous infusion over 24 to 72 h. Hypersensitivity reactions to ifosfamide plus mesna are not frequently described in the literature. Moreover, no reports exist concerning desensitization for this chemotherapy combination. Case presentation A 47-year-old man with stage IV renal sarcoma was treated with the combination of ifosfamide and mesna every 3 weeks in a 4-consecutive-day infusion protocol. During the second cycle of chemotherapy, he presented acute cutaneous symptoms. A 12-step desensitization protocol was proposed in view of the lack of knowledge of the possible hypersensitivity reactions to this combination of chemotherapy agents, and the multiple difficulties found during the study of the case. Conclusions The 12-step desensitization protocol was well tolerated. Therefore, it is an appropriate and safe option in the case of suspected allergy to ifosfamide plus mesna.

BackgroundIfosfamide is an antineoplastic agent with alkylating activity usually administered in combination with mesna. The latter is a thiol agent with uroprotective activity that prevents side effects such as haemorrhagic cystitis or nephrotoxicity which allows the administration of higher doses of ifosfamide without unwanted secondary effects. This combined treatment can be used for a wide range of tumours such as testicular, lung, lymphoma, and in advanced solid, soft-tissue sarcomas and gynaecological tumours. Ifosfamide-mesna is administered as a continuous infusion rather than in a bolus to avoid central nervous system toxicity.Case presentation A 47-year-old man with the diagnosis of stage IV renal sarcoma who received treatment with ifosfamide-mesna every 3 weeks in a consecutive 4-day infusion protocol. However, during the second chemotherapy cycle he presented urticarial lesions. In the absence of scientific evidence for risk of immediate reactions with this association, and given the lack of described experiences of allergic reactions with this chemotherapy combination, the aggressiveness of the tumour process, and the absence of validated skin tests, we proposed the completion of a 12-step desensitisation protocol.Conclusion The 12-step desensitisation protocol was well tolerated. Therefore, it is an appropriate and safe option in the case of suspected allergy to ifosfamide plus mesna. Keywords Ifosfamide plus mesna, desensitization, chemotherapy