When compared with nasopharyngeal carcinomas, ITCs are relatively low-grade tumors with a Ki67 index of approximately 10–30% and show diffuse positivity for CD5, whereas primary squamous carcinomas tend to display more keratinization, a higher histological grade with a Ki-67 labeling index exceeding 50%, and negativity for CD5 and S-100A9. Here, CD5 is linked to squamous cell carcinoma.