[Hypersensitivity to radiation therapy in a patient with tuberous sclerosis: biological considerations about a clinical case].

A 61-year-old man, with a tuberous sclerosis, experienced severe acute reactions during a concomitant chemoradiotherapy regimen after 22Gy and one cycle of 5-fluorouracil-cisplatinum. He was treated for a cervical squamous cell lymph node of unknown origin. Grade 3 mucitis and epitheliitis were observed only in the irradiated fields and required the end of the radiotherapy. Tuberous sclerosis is characterized by a loss of the TSC2 function, with a permanent activation of the mTOR pathway. Logically, some kind of "radioresistance" should be observed. Increased radiosensitivity is paradoxical. This case illustrates how radiosensitivity is a complex phenomenon and clinically unpredictable. Efficiency of the protocols associations of mTOR inhibitors and radiotherapy should be carefully scrutinized.