HLA-G and inverted papilloma: Additional file 1: Fig. S5 and Table S4 show that there was no significant difference in HLA-G expression between inverted papilloma and normal nasal mucosa (P > 0.05); However, with the progression of sinonasal papilloma and the onset of malignant transformation, the expression of HLA-G increases, which may be unrelated to HLA-G hypermethylation.