비·부비동 반전성 유두종에 관한 새로운 Pathologic Grading System

Background: Despite textbook classifications for the varied forms of sinonasal papilloma, surgical pathologists nationwide often find it difficult to specifiy the histopathological nature of agiven papilloma. Moreover, previous reports of clinicopathological analysis of inverted papilloma (IP) to predict recurrence and associated malignancy has confusing issues and remains controversial. Purpose : To verify the existing histopathological classification of sinonasal papillomas, and to evaluate histologically the role of inflammation in the pathogenesis and ongoing neoplastic development of IP. Furthermore, this study proposes a novel pathological staging system for IP and suggests a hypothesis regarding its pathogenesis. Materials and Methods: Pathological and retrospective chart review was performed in 41 patients with sinonasal papillomas who underwent surgery between 1995 and 2001. Results: Sinonasal papillomas are classified as exophytic squamous papilloma (14 cases), IP (25 cases), and cylindrical papilloma (2 cases). The IP are staged as I (3/25), II (15/25), III (7/25), and IV (3/25) according to histopathological findings. Stage I is the earliest lesion having ciliated respiratory epithelium with transition to squamous metaplasia or to matured squamous epithelium and can be easily confused with inflammatory polyp. Stage II is the most commonly found lesion. The surface mucosa has ciliated respiratory epithelium with partial loss and underlying squamous metaplasia resulting in exophytic growth. Nume-rous inflammatory cells such as polymorphonuclear leukocytes (PMNLs) and macrophages are present in the epithelium. The stroma shows active inflammatory cells infiltration and squamous metaplasia of ductal epithelium. Stage III is IP with dysplasia. The mucosa shows total loss of ciliated respiratory epithelium and the squamous metaplasia changes into stratified squamous epithelium containing atypical cells. Stage IV is IP with invasive squamous cell carcinoma that includes stage II and III lesions. Conclusion: Sinonasal papilloma is adequately classified according to exisitng descriptions. Moreover, IP can present in different histopathological stages within a given individual. IP can undergo dynamic transformation from a polyp-like appearance associated with inflammation to eventually become squamous cell carcinoma (SCC). This novel staging system can be used a foundaion to further understand the pathogenesis of IP and can be used to predict its recurrence and associated malignancy. (J Clinical Otolaryngol 2004;15:109–118)