KRT5 and carcinoma: For all the four cases that were included in the poorly-differentiated grade carcinoma category located in the tongue, submandibular area, maxillary and gingival sulcus, a marked reduction in the scores for the CK5 immunohistochemistry was observed; for squamocellular carcinoma originating from the tongue, a score of 1 was observed (Fig. 3C).