After induction of anesthesia by the anesthesia colleagues, rigid tracheoscopy is performed by <CLINICIAN_NAME>. This reveals inconspicuous mucosal conditions on all sides up to the tracheal bifurcation. Subsequent intubation of the patient by the anesthesia colleagues. Start of esophagogastroscopy. Insertion of the endoscope under visualization and constant air insufflation into the stomach. This reveals a slightly erosive gastric mucosa relief on all sides, but without any evidence of a tumor. Entering in inversion. Inspection of the gastro-oesophageal junction. Mucosal changes due to reflux can be seen here. After desufflation, slow withdrawal of the endoscope with circular inspection of the entire esophagus. Here, especially in the area of the distal and middle third, there are flat, uneven mucosal changes with whitish deposits, which can be partially scraped off. A thrush esophagitis can be considered in the differential diagnosis. However, to rule out malignancy, biopsies are taken from a total of 3 conspicuous, uneven areas. (44 cm, 34 and 30 cm from the alveolar ridge). Then proceed to pharyngo-laryngoscopy: insertion of the size B Kleinsasser tube and adjustment of the endolarynx. This also reveals uneven, postradiogenically altered mucosal conditions on all sides. In the area of the glottic plane there is Reinke's edema on both sides, right > left. Otherwise no evidence of a tumor. Adjustment of the posterior commissure. Here, too, there is no evidence of tumor growth. Only in the area of the left arytenoid hump is there an uneven change in the mucosa which is biopsied. Subsequently, the right and left piriform sinuses are entered. This can be freely unfolded and is lined with postradiogenically altered smooth mucosa up to the tip of the piriform sinus. Also inconspicuous mucosal conditions in the area of the esophageal entrance and postcricoid. Setting of the vallecula. Here, too, only postradiogenically altered mucosa without evidence of tumorous growth. In the area of the left base of the tongue, the mucosa is inspectably uneven and partially covered. Therefore biopsy in the area of the left base of the tongue. Hemostasis by means of monopolar coagulation. Otherwise unremarkable mucosal conditions in the rest of the oropharynx. Subsequent insertion of the reinforced retractors and looping of the tongue. The lesion described above is seen in the area of the left middle edge of the tongue with external histological suspicion of squamous cell carcinoma. Marking of the resection margins using the electric needle with a safety distance of at least 1 cm on all sides. Then resection of the area with the monopolar needle. Resection of the ulcer using the scissors. Hemostasis using bipolar coagulation. Suture marking is still performed in situ (ventral suture marking long long, inferior suture marking short short). Hemostasis using bipolar coagulation. Clinically macroscopically, a wide in sano resection of the ulcer was performed. After consultation with <CLINICIAN_NAME>, the tumor resected in toto for definitive histology. Subsequent completion of the operation without complications. Conclusion: Clinical macroscopic in sano resection of a left tongue marginal ulcer with externally histologically expressed suspicion of squamous cell carcinoma. Furthermore, multiple biopsies in the area of the esophagus with extensive changes in the mucosa. A thrush esophagitis can also be considered in the differential diagnosis. If malignancy in the area of the esophagus is excluded, a gastroenterological evaluation and treatment should be initiated. Further procedure after receipt of the definitive histology.