[Immunohistochemical study of p53 and Ki-67 in inverted papillomas and nasal polyps arising from nasal or paranasal regions].

The current study investigated immunohistochemical features of p53 and Ki-67 in 12 cases of paranasal inverted papillomas (IPs) and 14 cases of nasal polyps (NPs). Four IPs were accompanied with squamous cell carcinoma (SCC) or dysplastic lesions (DL). The p53 expressions were evaluated by "p53 score", which was defined by combined number and intensity of p53 positive cells. Ki-67 expression was evaluated by the labeling index. In both IPs and NPs, p53 expression was statistically correlated with Ki-67 index. These findings suggested the correlation among the p53 dysfunction and the aggressive epithelial growth in both IPs and NPs. The p53 expression was recognized in 9 IPs (75%), and in 6 NPs (42.9%), respectively. There were no significant differences in p53 scores and Ki-67 index between IPs and NPs. However, the distribution patterns of p53 positive cells in IPs appeared to be different from those in NPs. These immunohistochemical features may play a role in differentiating IPs from NPs. On the other hand, the p53 scores of SCC areas and Ki-67 index were significantly larger than those of IPs without SCC/DL or those of NPs (p<0.05). These results would indicate the importance of p53 in malignancy. However, our results also raise a caution that p53 expression in NPs can occur in similar staining patterns to SCC and its recognition is necessary in differentiating NPs from malignancy.