PMC6489553_01
MRI of the nasal cavity and paranasal sinuses. (A) Contrast-enhanced MRI shows a huge tumor located in the nasal cavity and paranasal sinuses eroded not only the adjacent bone but also bilateral frontal lobes. (B) Contrast-enhanced MRI shows the tumor was almost completely disappeared 1 month after radiotherapy and chemotherapy.. Abbreviation: MRI, magnetic resonance imaging.
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The maximum diameter of the tumor was 7.0x5.2 cm, and the tumor eroded the adjacent bones including the bilateral maxillary sinus medial wall, sieve plate, sphenoid sinus, frontal sinus wall and bilateral frontal lobes (Figure 1A). After chemoradiotherapy, the treatment led to almost complete remission (CR) as assessed with the Response Evaluation Criteria in Solid Tumors (RECIST 1.1) (Figure 1B), and no adverse reactions were reported.
Histopathology of LCNEC. (A) H&E staining: tumor cells in the subepithelial stroma showed nest infiltration. The cells are large in volume, rich in cytoplasm and vacuolated or eosinophilic and have a large nucleoplasmic ratio. The nucleus is round or elliptical, the chromatin is deeply stained, and the granules are coarse and granular, and the obvious eosinophilic nucleoli can be seen (400xmagnification). Immunohistological staining showing tumor positivity for CD56 (B), CgA (C), CKpan (D), Ki-67 (E) and Syn (F).. Abbreviation: LCNEC, large-cell neuroendocrine carcinoma.
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The final histological examination showed LCNEC with poor differentiation (Figure 2).