The diagnosis and management of malignancies of the temporal bone remain an area that presents a severe challenge to the otolaryngologist. The complex anatomy of the temporal bone and surrounding neurovascular structures mandates that any surgeon who undertakes a formidable procedure such as temporal bone tumor resection have an intimate knowledge of the galaxy of anatomic details of this area. Familiarity with patterns of invasion of these malignancies is a prerequisite. Advanced imaging with computed tomography (CT) and magnetic resonance imaging (MRI) has greatly enhanced preoperative evaluation and surgical planning, but there is still no uniformly accepted staging system for these tumors.

Primary malignancies of the temporal bone are rare.1 Squamous cell carcinoma (SCC; also abbreviated SCCA) is the predominant primary carcinoma arising from the external canal and middle ear.² Adenoid cystic carcinoma is the next most common, although its incidence is far below that of SCC.³ Papillary tumors of the temporal bone (also classified as adenomas or adenocarcinomas) are thought to arise from the endolymphatic sac.⁴,⁵ The temporal bone can be secondarily invaded by cancer of the pinna, parotid, and temporomandibular joint (TMJ). Although rare, the temporal bone can be the focus of metastasis from distant sites (e.g., breast, lung, kidney, thyroid, larynx), that are thought to be hematogenous to the petrous apex.⁶ In children, rabdomyosarcoma is the most frequent somatic tumor and carries a poor prognosis, although combined therapy (surgery, radiotherapy, and chemotherapy) has improved the outlook. Early diagnosis, which is difficult, is essential to a favorable outcome.

Diagnosis

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.

Management

In 1954, Parsons and Lewis⁹ reported their landmark paper on en bloc subtotal resection of the temporal bone and introduced the present day concept for management of the temporal bone malignancies. Conley and Novack,^{1, 4}

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