Skull Base Inverted Papilloma: A Comprehensive Review
Table 5
Krause staging system (2000) for inverted papilloma [324].
Stage
Location and spread
Malignant changes
T1
Tumor totally confined to the nasal cavity, without extension into the sinuses. (The tumor can be localized to one wall or region of the nasal cavity or can be bulky and extensive within the nasal cavity but must not extend into the sinuses or into extranasal compartment)
There must be no concurrent malignancy
T2
Tumor involving the ostiomeatal complex, and ethmoid sinuses, or the medial portion of the maxillary sinus, with or without involvement of the nasal cavity.
There must be no concurrent malignancy
T3
Tumor involving the lateral, inferior, superior, anterior, or posterior walls of the maxillary sinus, the sphenoid sinus, or the frontal sinus with or without involvement of the medial portion of the maxillary sinus, the ethmoid sinuses, or the nasal cavity
There must be no concurrent malignancy
T4
All tumors with any extranasal/extrasinus extension to involve adjacent, contiguous structures such as the orbit, the intracranial compartment, or the pterygomaxillary space
