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6.14 External Auditory Canal & Middle Ear

​Updated: May 2003

These tumours require an adequate radiological investigation to determine the real extent of the disease prior to any definite treatment as often they are more extensive than clinically apparent.

1. External Auditory Canal

Surgery

A sleeve resection and a skin graft are occasionally possible for "in situ" and early lesions but have limitations related to the ill-defined boundaries of the tumour, and surgery may be incomplete.

A lateral temporal bone resection or subtotal temporal bone resection may be necessary in order to remove the tumour completely.

Radiation Therapy

External beam treatment may be considered as an alternative to surgery or used postoperatively when resection margins are close or uncertain. Treatment volume is designed to cover the potential areas of involvement while minimizing unnecessary irradiation to the adjacent vital organs (eye and brain). Treatment is usually prescribed post-operatively.

2. Primary Carcinoma Involving the Petrous Temporal Bone

Surgery

Subtotal or partial temporal bone resection followed by postoperative radiotherapy is the curative treatment standard whenever possible.

Radiation Therapy

External beam radiation is used when surgery is not possible and is usually not curative.

Glomus Tumours (Chemodectoma)

The primary treatment of these benign tumours when small and accessible (glomus tympanicum) should be surgical. Most conditions, however, require radical surgical approaches with significant morbidity in view of the tumour location in the temporal bone and proximity to the jugular vein and carotid artery.

Radiotherapy may be recommended larger glomus tumours (glomus jugularis) where surgery will be incomplete or where surgical morbidity is significant.

Lymph Node Metastases to the Neck Secondary to an Unknown Primary

Cervical lymphadenopathy is a common clinical problem that is usually associated with infection or inflammation. When this fails to respond to apparently appropriate treatment, malignancy should be suspected. Although many patients with head and neck cancer present with enlarged nodes in the upper two thirds of the neck, approximately five per cent will still have an occult primary after full clinical and radiological investigation. Excluded from this discussion are patients presenting with metastases in the supraclavicular fossa (who are likely to harbour a primary in the thyroid or below the clavicles) and those with known metastatic disease elsewhere.

Evaluation of the patient with enlargement of the neck node(s) should include:

  1. Full history, general clinical examination and a thorough examination of the head and neck
  2. If the clinical examination is negative, a fine needle aspiration biopsy should be performed
  3. Chest X-rays
  4. EB virus antibody titres (IgA ECA) in patients at high risk of nasopharyngeal cancer
  5. CT scan of the head and neck
  6. Examination under anesthetic and panendoscopy of the upper airways with esophagoscopy and bronchoscopy if clinically indicated or for patients with lumph nodes in the lower neck. Biopsies should be taken from sites likely to harbour the primary such as the nasopharynx, tonsils, base of tongue, lateral pharyngeal walls and pyriform sinuses.
  7. MRI may be considered in individual cases and PET has been reported to be helpful in some cases.
  8. If the above is negative or unsatisfactory, an excisional biopsy of the node metastases may be performed to obtain an adequate histopathological diagnosis prior to definite treatment.

Having established the diagnosis and completed the recommended work-up, subsequent treatment will depend on individual circumstances. Clinical experience and several publications have shown that this condition is potentially curable with survival rates similar to other head and neck malignancies. Radiation therapy is most commonly used for squamous cell carcinoma, but in the absence of randomised trials, optimal management continues to be debated.

Squamous Cell Carcinoma

In general, when the primary is thought to be in the adjacent upper airway, a course of radical radiotherapy will usually be recommended to include the likely primary sites and at least the ipsilateral neck. When there is a high probability of a primary in the nasopharynx - such as in Asian patients with poorly differentiated carcinoma in an upper neck node- bilateral neck irradiation is indicated. Subsequent CT scanning and surgical management of the neck will follow according to the usual guidelines for neck dissection.

Adenocarcinoma

It is usually assumed that these metastases have come from a primary salivary gland carcinoma and surgical treatment is recommended.

Follow-up

This should be along the same lines as for other head and neck cancers with particular attention to the early detection of potential emerging primaries.

SOURCE: 6.14 External Auditory Canal & Middle Ear ( )
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