OBJECTIVETo investigate the clinicopathological features and prognosis of patients with the malignant transformation of sinonasal inverted papilloma.

METHODSThirty-two consecutive cases encountered between January 1991 and January 2008 were retrospectively reviewed. Survival rates and prognostic factors were calculated with SPSS 17.0 software using the Kaplan-Meier method and multivariate Cox model survival analysis.

RESULTSThe malignancy accounted for 8.99% of all types of sinonasal inverted papilloma. There were 25 males and 7 females, the median age was 56.5 years. The sites of tumor included 22 cases in nasal cavity and ethmoid sinuses, 10 cases in maxillary sinuses. The tumors included 21 high grade tumors, 8 intermediate grade tumors and 3 low grade tumors. Thirty-two patients were staged as T1(3/32), T2(10/32), T3(16/32), T4(3/32). According to the percentage of the malignant cell in the entire tumor tissue, 5 patients were in grade I, 5 patients were in grade II, 8 patients were in grade III, 14 patients were in grade IV. There were 3 distant metastasis in 32 patients; 19 patients underwent surgery plus postoperative radiotherapy, 10 underwent surgery alone and 3 underwent radiotherapy alone. The 5-year overall survival were 72.5%, and the median overall survival time was 62.2 months. Kaplan-Meier univariate survival analysis indicated that the clinical stages and treatment modalities were prognostic factors, and multivariate Cox model survival analysis confirmed that the clinical stages and treatment modalities were independent factors for overall survival (HR were 4.211 and 0.312, all P < 0.05).

CONCLUSIONSThe morbidity of sinonasal inverted papilloma-associated malignancy is low, the clinical features were not specificity. The clinical stages and treatment modalities may affect the prognosis. Surgery plus postoperative radiotherapy are main treatment means.