Malignant Tumors of the Temporal Bone Workup

Updated: Jul 12, 2018
  • Author: Stephanie A Moody Antonio, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Workup

Laboratory Studies

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  • Routine preoperative testing includes CBC counts, electrolyte level tests, renal function tests, liver function tests, and coagulation studies (if warranted based on the patient's history of bleeding and current medications).

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Imaging Studies

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  • CT scanning of the temporal bone and neck: A physical examination alone cannot adequately evaluate the extent of tumor extension beyond the pinna. Specific radiographic information is crucial for accurate preoperative staging. Obtain a fine-cut (1 mm) high-resolution CT scan of the temporal bone. The radiologist should evaluate the study specifically for EAC erosion, middle ear involvement, otic capsule erosion, mastoid involvement, jugular fossa erosion, carotid canal erosion, tegmen erosion, and posterior fossa involvement. The facial nerve, stylomastoid foramen, temporomandibular joint, parotid gland, and infratemporal fossa should also be carefully examined.

  • Magnetic resonance imaging: CT scanning may be unreliable to differentiate fluid and inflamed mucosa from a tumor in the middle ear and mastoid, especially when no bony erosion is present to raise the suspicion for the presence of a tumor. In addition, spread along fascial planes and neurovascular structures can be very difficult to detect. In these situations, MRI with gadolinium enhancement can be helpful because it better delineates soft tissue interfaces.

  • Chest radiography: If the histology indicates squamous cell carcinoma, obtain plain radiographs or CT scans of the chest to rule out metastasis.

  • CT scanning of the chest, abdomen, or pelvis: CT scanning of the chest, abdomen, or pelvis is not necessary unless the biopsy specimen of the temporal bone tumor reveals a tumor with a known propensity for metastasis. This type of tumor includes melanoma, adenocarcinoma, lymphoma, and renal cell carcinoma.

  • Carotid angiography with balloon occlusion Xenon test: If the carotid artery is suspected to be involved, angiography with ipsilateral balloon occlusion Xenon testing is performed to demonstrate the adequacy of cerebral blood flow from the contralateral carotid artery. Special attention is also given to the venous outflow phase to determine the adequacy of the contralateral sigmoid/jugular system in case the surgery requires sacrifice of the sigmoid sinus or internal jugular vein.

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Other Tests

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  • Audiometry: An audiogram is obtained prior to performing any major procedure on the ear or temporal bone. Audiograms provide baseline hearing thresholds for future comparison.

  • Electrocardiography

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Diagnostic Procedures

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  • Biopsy: Obtain a biopsy to determine whether the lesion in the ear is benign or malignant. A needle biopsy can be performed if most of the mass is subcutaneous or in the parenchyma of the parotid gland. A staging mastoidectomy is not appropriate.

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Histologic Findings

Although CT scanning provides important preoperative staging information, systematic pathologic evaluation of the specimen is crucial for staging and treatment. For example, if pathologic evidence of bony invasion or soft tissue spread is found but was not predicted by findings on preoperative imaging studies, the stage may be adjusted and adjuvant therapy considered.

The surgeon should personally orient the surgical tissue for the pathology team. The pathologist should then examine multiple sections of key elements (eg, bony EAC, facial canal, otic capsule, tympanic ring, bony-cartilaginous junction). The soft tissue margins at the stylomastoid foramen, infratemporal fossa, and facial nerve (if resected) should be detailed. Also, mucosal samples of the middle ear and mastoid should be specifically examined.

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Staging

Staging systems are intended to help classify patients preoperatively into groups whereby decisions regarding treatment may be made on the basis of comparison to previously treated patients with similar tumor characteristics (ie, the stage). To date, no staging system for temporal bone malignancies is universally accepted. Several factors impede the process of developing a staging system, including the rarity of the tumors, the impossibility of evaluating disease extent by physical examination alone, and the unreliability of radiographic studies to determine the extent of disease in certain situations.

Many authors have proposed staging systems concurrent with a review of patient series from major institutions; however, the small number of patients per group, the disparity of staging criteria, the diversity in management protocols, and the use of nonstandardized surgical nomenclature prohibits meaningful comparison of outcomes. In addition, some patients are reportedly classified into groups with variability in histology types and sites of tumor origin, which further confounds analysis of outcome by stage.

Numerous staging systems have been proposed; however, to date, no universally accepted staging system for temporal bone cancers exists. A staging system for squamous cell cancers of the EAC proposed by the University of Pittsburgh has been shown useful and has gained support in the literature. [11, 12, 13, 8, 4, 14] This staging system is based on clinical, radiologic, and pathologic findings. In general, tumors that are limited to the EAC are defined as early disease, and those that extend beyond the external canal to invade the surrounding soft tissues, the middle ear, the mastoid, or CNs are recognized as advanced disease.

In the original staging system proposed by Pittsburgh, lesions were defined as follows: [11]

  • T1 - Tumor limited to the EAC without bony erosion or evidence of soft tissue involvement

  • T2 - Tumor with limited EAC bone erosion (not full thickness) with limited (< 0.5 cm) soft tissue involvement

  • T3 - Tumor eroding the osseous EAC (full thickness) with limited (< 0.5 cm) soft tissue involvement or tumor involving the middle ear, mastoid, or both

  • T4 - Tumor eroding the cochlea, petrous apex, medial wall of the middle ear, carotid canal, or jugular foramen of dura; or with extensive soft tissue involvement (>0.5 cm), such as involvement of the temporomandibular joint or stylomastoid foramen; or with evidence of facial paresis

The Pittsburgh staging system has become widely applied in case reports of temporal bone cancer. [4, 15]

The Pittsburgh staging system was modified by the authors after further review of patients from an extended series. [9] In the modified staging system, facial nerve weakness is considered a criterion for a T4 lesion. The authors observed that facial nerve paresis did not occur in lesions otherwise classified as limited T1, T2, or T3 lesions. Involvement of the facial nerve would be otherwise classified as T4 based on the anatomical area of involvement, including the medial wall of the middle ear (horizontal segment), extensive bony erosion within mastoid (vertical segment), or involvement of stylomastoid foramen. In the T4 group, survival was similar between patients with and without facial paralysis (unpublished). A few reports have used the modified staging system. [16]

Nodal involvement and stage can be classified as it is for other cancers of the head and neck.

  • N1 - Single ipsilateral lymph node, size less than 3 cm

  • N2 - Single ipsilateral node, size 3-6 cm

  • N2b - Multiple ipsilateral nodes, all less than 6 cm

  • N2c - Bilateral or contralateral nodes, all less than 6 cm

  • N3 - Nodes involved greater than 6 cm

Cancer is staged as follows:

  • Stage 0 - Tis N0 M0

  • Stage I - T1 N0 M0

  • Stage II - T2 N0 M0

  • Stage III - T3 N0 M0, T1 N1 M0, T2 N1 M0, T3 N1 M0

  • Stage IV - T4 N0 M0, T4 N1 M0, any T N2 M0, any T N3 M0, any T any N M1

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