aged; case report; clinical article; computer assisted tomography; coronavirus disease 2019; dermatitis/co [Complication]; female; gingiva bleeding; head and neck cancer/rt [Radiotherapy]; histopathology; human; human tissue; hypertension; hypothyroidism; irradiation; letter; mucosa inflammation/co [Complication]; neck dissection; planning target volume; segmental mandibulectomy; skin manifestation; skin toxicity/co [Complication]; squamous cell carcinoma; tracheostomy; volumetric modulated arc therapy; antiinfective agent/pv [Special Situation for Pharmacovigilance]; face mask; minimally 94 percent efficient filtering facepiece respirator