Recurrent inverted papilloma coexisted with skull base lymphoma: A case report

Figure 2 Histological examinations. A and B: Hematoxylin and eosin (H/E, 20 ×) sections showed an inverted papilloma with an inward growth pattern, which is composed of the proliferating columnar and squamous epithelial cells; C: H/E (100 ×) section showed medium to large tumor cells with oval to round shape, occasional poly-lobulated, vesicular nuclei containing fine chromatin and several nuclear membranes, with bound nucleoli infiltrating within the nasal stroma and brain tissue; D: Immunohistochemically, the tumor cells were positive for Bcl-2; E: Immunohistochemically, the tumor cells were negative for Bcl-6; F: The Ki-67 index was approximately 90%-95%.