HE and immunohistochemical (Ki-67, CD31, P53) staining of primary (A, B, C, D) and relapsed (E, F, G, H) cancer tissues. H&E staining (A) showed irregular nests of squamous cell carcinoma dispersed in the stroma, with various quantities of inflammatory cells infiltrating the stromal tissues as well as cancerous nests. In the relapsed cancer tissue (E), neutrophils were more predominant, whereas in primary cancer tissues, a mixed population of lymphocytes and neutrophils was observed. The immunohistochemical staining patterns of Ki-67 (B, F), CD31 (C, G), and p53 (D, H) were similar in the primary and relapsed tissue. Ki-67 positively expressed in >90% of tumor cells. P53 was strongly expressed in tumor cells.