Fig. 3

Magnetic resonance images (T1 enhanced sequence images) and H&E staining images (20 ×) of primary site tumor before and after two courses of chemo-immunotherapy. Patient 6(A) and patient 7(B), suffering the squamous cell carcinoma at the mandible (T4aN1M0) and gingiva (T2N3bM0) respectively. As for patient 6, the maximum diameter of tumor was about 23 mm before neoadjuvant treatment, which was significantly enhanced on enhanced scan. After neoadjuvant treatment, the maximum diameter of tumor was still about 23 mm, and the intensity of enhancement was not significantly reduced. For patient 7, before neoadjuvant treatment, the maximum diameter of tumor was about 32 mm, which was also significantly enhanced on enhanced scan. Though the maximum diameter of tumor shrank to about 25 mm after neoadjuvant treatment, and the intensity of enhancement was significantly reduced, the radiological response was still assessed to be SD. Surprisingly, both of them achieved pCR at the primary site after two courses of chemo-immunotherapy. Histopathological assays of pre-treatment show numerous infiltrating tumor nest with nuclear enlargement, nuclear hyperchromasia, prominent nucleoli and mitotic figures, which conforms to the characteristics of cancer cells.After treatment, histopathology revealed interstitial fibrous tissue hyperplasia, infiltration of multinucleated giant cells and chronic inflammatory cells (including lymphocyte and plasma cells infiltration), and no residual tumor inside the tumor bed. Histopathology revealed interstitial fibrous tissue hyperplasia, infiltration of multinucleated giant cells (arrows) and chronic inflammatory cells (including lymphocyte and plasma cells infiltration), and no residual tumor inside the tumor bed