[Clinicopathological investigation of malignant alteration in nasal and paranasal sinus papilloma using flow cytometric DNA ploidy].

Among tumors of the head and neck, nasal and paranasal sinus papilloma is a relatively rare benign tumor. However, it is different from other benign nasal and paranasal tumors, in histological morphology, and in higher probabilities of recurrence, complication with malignant tumor, and malignant alteration. In this study, we examined clinically and pathologically 30 patients with nasal and paranasal sinus papilloma who underwent operations in our department between 1975 and 1994. The tumor occurred in the opening of the maxillary sinus in 19 patients and in the nasal septum in 7 patients. Destruction of bone was observed in 12 patients. Pathological examination revealed inverted papilloma in 17 patients, exophytic papilloma in 13 patients, and atypia in 4 patients. Recurrence was observed in 9 patients, and malignant alteration was observed in 5 patients. Using paraffin sections, aneuploidy was assessed by flow cytometric DNA ploidy. Diploid in 25 cases (83.3%) and aneuploid in 5 cases (16.7%) were observed. Risk factors of malignant alteration in nasal and paranasal papilloma are considered to be 1) developmental morphology, 2) destruction of bones, 3) atypia in pathology, 4) recurrence before progression to malignancy, and 5) the presence of aneuploidy. The 5 patients in whom malignant alteration was observed each showed 4 of the 5 risk factors, suggesting that malignant alteration is most likely to occur in nasal and paranasal papilloma that show 4 or 5 risk factors. The period up to malignant alteration varies; in one patient, it was more than 10 years. Therefore, follow-up observation over a long period is required.