An unexpected skin ulcer and soft tissue necrosis after the nonconcurrent combination of proton beam therapy and pazopanib: A case of myxofibrosarcoma

We herein report the case of a patient presenting with myxofibrosarcoma (MFS) who underwent treatment with surgery, proton beam therapy (PBT), and pazopanib. A 64-year-old male was diagnosed with MFS, which ranged from the posterior neck to the shoulder. Surgery was performed as an initial treatment; however, the primary tumor recurred 83 months after the initial treatment. We, therefore, administered PBT. Although most of the recurrent tumor disappeared after PBT, multiple lung metastases were identified 3 months after the completion of PBT. We initiated antiangiogenic treatment with pazopanib. Although long-term survival was achieved with the treatments, the patient suffered from a skin ulcer and soft tissue necrosis and eventually died of general prostration caused by infection, and complicated by pneumonia. Although PBT and pazopanib were effective for treating the local recurrence and lung metastases of MFS, respectively, clinicians must be cognizant of the fact that the combination of high-dose irradiation and angiogenesis inhibitors, even in nonconcurrent cases, can result in a severe skin ulcer and soft tissue necrosis.