Fig. 3

a A porcine tongue with pseudotumors lies in front of the participant. The participant (left) holds a scalpel and forceps to perform tumor resection on the pseudotumor model. At the same time, the participant can orient himself on the CT image displayed on a laptop computer. b Porcine tongue with four injected pseudotumors. The red circled areas show the pseudotumors which are slightly visible. The injection site was closed with resorbable suture material using the single-button technique. c CT image of the soft tissue window of a porcine tongue showing two pseudotumors as round radio-opaque masses (outlined in red) in sagittal plane. d Representation of two pseudotumors in ultrasound (left and right), both are outlined in red as echogenic structures. The right pseudotumor clearly shows a dorsal acoustic attenuation. e Macroscopic evaluation of the pseudotumor, which was cut in slices of equal thickness (3–5 mm), arranged from left to right in the order of sectioning. In the center is the white pseudotumor (outlined in red). The epithelium of the tongue mucosa (highlighted in green) is also well visible. The borders of the resection can be measured from the image. The white scale bar has a width of 20 mm. f Schematic representation of a pseudotumor slide. Resection borders with the corresponding categories for evaluation: positive margin (asterisk, dark purple), close margin (circle, light purple), clear margin (triangle, light green), and excessive margin (rectangle, dark green)