Salivary gland tumours

Benign and malignant salivary gland tumours can arise from the parotid gland, submandibular gland and rarely the sublingual gland. They typically present as a parotid or sub-mandibular mass. Approximately 10% of parotid and 50% of submandibular gland tumours are malignant. Both ultrasound and FNA are useful in delineating the nature of the salivary gland lesions. A CT scan may be required to evaluate a complex mass such as deep lobe tumours and invasive tumours. Common benign tumours are pleomorphic adenoma and Warthin's tumour (papillary cystadenoma lym-phomatosum). Pleomorphic adenoma is usually rubbery firm in consistency and may recur if not excised with an adequate margin. Warthin's tumour may be bilateral and tends to occur in the elderly. Malignant salivary gland tumours include mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, adenocarcinoma, undifferentiated carcinoma, squamous cell cacinoma and lymphoma. Metastases to the parotid gland can originate from the scalp, cheek, nasopharynx and oral cavity. Superficial parotidec-tomy via a preauricular incision is the recommended minimal surgical procedure. Open incisional biopsy should be avoided due to the concern for facial nerve damage and unsightly scarring. When malignancy is confirmed by intraoperative frozen section, total parotidectomy and sampling of the jugulodigastric lymph node are recommended. The facial nerve is preserved unless directly involved by the tumour. When the facial nerve or its major branches are scarified, a nerve graft is desirable. Radical neck dissection is necessary in the presence of clinically evident cervical nodal metastasis. Prognosis is dependent on the size and grade of the malignant tumour. For high-grade tumours, postoperative radiotherapy is recommended.

Parapharyngeal space tumours

The parapharyngeal space (lateral pharyngeal space) is a pyramid-shaped loose fascial plane around the pharynx

Figure 20.20. Pleomorphic adenoma of the deep lobe of the parotid gland being dissected out of the parapharyngeal space.

between the skull base and the hyoid bone (Figs 20.17 and 20.20). Tumours of the parapharyngeal space can present as an upper neck mass or submucosal oropharyngeal mass. They may be salivary gland tumours, neurogenic tumours, carotid body tumours, vascular tumours, lymphomas and miscellaneous soft-tissue tumours (e.g. lipoma). Treatment is surgical excision by transcervical or parotidectomy approach.

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