Lisan Q, et al. - The possibility of a tie-in between the Krouse classification and the recurrence rates of sinonasal inverted papilloma were inspected. A 51% increased tendency of recurrence was reported in the inverted papillomas, classified as stage T3 according to the Krouse classification system. Head and neck surgeons were cautioned to be aware of this tendency when planning and performing surgery for sinonasal inverted papilloma.