LAUSR

Quad shot (QS) radiation is a palliative treatment regimen consisting of 2 days of twice-daily radiation fractionation repeated every 3-4 weeks for up to 3 cycles to a total dose of 42-45 Gy in 12 fractions. While rare instances of soft tissue necrosis following QS regimens have been reported in the re-irradiation setting, we report a first case of radiation-induced brain necrosis following initial QS treatment. The patient is a 55-year-old man who presented with headaches, nosebleeds, and oral numbness. Nasal endoscopy revealed a sinus mass. Subsequent imaging showed a 4.4 cm lesion arising from the left nasal cavity with invasion through the cribriform plate and anterior planum with epidural extension. He underwent tumor debulking. Pathology revealed HPV-related multiphenotypic sinonasal carcinoma. Metastatic disease was additionally discovered in the lungs, liver, bones, and brain. He received systemic therapy and palliative radiation. Palliative radiation included QS photon external beam radiation to the primary sinonasal lesion using 3 cycles of 14 Gy in 4 fractions. Short-term MRI after treatment revealed interval decrease in size of the sinonasal lesion, 15 months following QS radiation, brain MRI revealed increasing hyperenhancement of the right gyrus rectus with associated FLAIR hyperintensity. Perfusion analysis demonstrated no abnormally increased relative cerebral blood volume (rCBV). Follow-up imaging over the subsequent 6 months showed increasing irregular enhancement in bilateral anteromedial temporal lobes and gyrus rectus, worsening of surrounding FLAIR hyperintensity, development of satellite enhancing lesions, and increased rCBV on perfusion imaging. The patient was evaluated by a neuro-oncologist and prescribed bevacizumab to treat radiation-induced brain necrosis. At this time, the patient reports dysosmia and intermittent cranial discomfort but denies additional neurologic symptoms. Palliative QS therapy offers favorable response rates for incurable head and neck cancers. This report raises attention to the possibility of QS radiation-induced necrosis as a rare but potential adverse effect.