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case_images: Nasopharyngeal endoscopic and radiological examinations. (A) Nasopharyngeal endoscope displayed an irregular mass obstructing the right nasal cavity. (B and C) Coronal and axial computed tomograms (CT) of the head and neck revealed an irregular mass in the right inferior nasal meatus blocking the whole right nasal cavity (white arrow).
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case_images: NPC (T4N0M0), which had undergone successful radiotherapy 10 years earlier. Nasopharyngeal endoscopic examination revealed that the right nasal cavity was obstructed by an irregular mulberry-like lesion in the right inferior nasal meatus, which had a large amount of purulent material on the surface and was easily bleeding when touched (Figure 1A). A computed tomogram (CT) of the head and neck showed an irregular mass blocking the entire right nasal cavity, and there was no lesion was found in the nasopharynx (Figure 1B and C). 
case_images: Histological features of the sinonasal neoplasm. (A) Low power view revealed that the tumor consisted of two sharply disparate separated components (hematoxylin and eosin [H&E], x40). (B) The PSCC component had a complex papillary structure with a fibrovascular core and obvious atypia of the surface epithelium lacking keratinization (H&E, x100). (C) The small blue roundish to spindle component was heterogeneous and located within the stroma (H&E, x200). (D) High power view showed that the second type of tumor cells were poorly differentiated with scarce cytoplasm and hyperchromatic pepper-salt-like nuclei (H&E, x400).
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case_images: Histologically, the neoplasm consisted of two well-defined distinct components (Figure 2A). The principal component was PSCC, an unconventional non-keratinized squamous cell carcinoma with a complex papillary architecture, which accounted for about 70% of the tumor (Figure 2B). This component accounted for the remaining 30% of the tumor (Figure 2C and D). 
case_images: Immunohistochemical and in situ hybridization features of the sinonasal neoplasm. (A) AE1/AE3 was diffuse positive for the squamous component and partially weakly positive for the small blue round or fusiform component (black arrow). (B) P40 was diffuse positive for the squamous component and negative for the small blue round or fusiform component. (C and D) Syn and CgA were diffuse positive for the small blue round or fusiform component and negative for the PSCC component. (E) The Ki-67 indexes of these two entities were up to 50% and 90%, respectively. (F) EBV in situ hybridization were negative for these both portions [All figures magnification, x200].
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case_images: The PSCC component was diffuse positive for AE1/AE3 and P40, while it was negative for two neuroendocrine markers such as synaptophysin (Syn) and chromogranin A (CgA) (Figure 3A-D). Conversely, the small blue round or fusiform component was diffuse positive for Syn and CgA, while AE1/AE3 was partially weakly positive and P40 was negative (Figure 3A-D). The Ki-67 labeling index of the PSCC component was up to 50%, while the small blue round or fusiform component was up to 90% (Figure 3E). In situ hybridization for Epstein-Barr virus (EBV) was negative in both components (Figure 3F).