RESUMEN
Toxic epidermal necrolysis [TEN] is a severe drug induced type IV hypersensitivity syndrome that can be caused by anticonvulsant drugs, especially the aromatic anticonvulsants such as phenytoin. Most patients with brain metastasis receive whole brain radiotherapy along with anti-edema measures and anticonvulsants either as prophylactic or for symptom control; phenytoin being the most commonly used drug. In a subset of patients, cranial irradiation may act as a precipitating factor along with anticonvulsants for the development of TEN. We report a 54-year-old patient with metastatic non-small cell lung cancer treated with palliative whole brain and mediastinal radiotherapy with concurrent phenytoin-developing TEN, which started within the radiation portals with subsequent generalization. Though a rare, but serious complication, avoidance of the use of phenytoin concurrent with radiotherapy, replacing phenytoin with newer anticonvulsants, early recognition, aggressive management and awareness of this possible complication has been implied upon in this report