The diagnosis of SCC of the external canal and middle ear is often made late in the disease because of long-standing suppurative disease. By the time the diagnosis is made, the tumor may have involved the carotid canal, dura, facial nerve, and extended into the temporomandibular (TMJ) or pterygoids. It is important in assessment of these patients to be familiar with the behavior patterns of these tumors. Leonette et al.3

described five patterns of invasion as determined by CT and MRI findings correlated with operative and pathologic findings. They described anterior, inferior, medial, superior, and posterior extension. In other words, extension occurs in all directions, including natural pathways such as the fissures of Santorini.3

CT is essential for staging. MRI is helpful in determining soft tissue invasion including dural involvement and pterygoid involvement. Curtin et al.7 have proposed what has become known as the Pittsburgh Staging System for SSC of the temporal bone. In their system, T1 is a tumor limited to the external canal with no bone erosion, T2 includes erosion of the bony canal, T3 tumor involves middle ear and/or mastoid, and T4 is a tumor involving petrous apex, carotid canal, jugular, foramen, and soft tissue involvement. In my view, this system of staging is the best yet proposed but still is not entirely satisfactory. Further staging refinements will require that subclassifications of staging include dural and skull base involvement, as suggested by Clark et al.8 inasmuch as anterior extension carries a better prognosis than medial and posterior extension and should be identified in the staging system. I suggest modifying the Pittsburgh Staging System to include Clark's subdivision of extratemporal spread. Curtin's T4 would become a T4a, T4b would include intracranial involvement of dura, brain, and cranial nerves.

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