Salivary gland tumours

Parotid bed with main trunk and upper and lower divisions of facial nerve exposed following tumour resection.

Salivary Gland Tumours in New Zealand: An Overview with a Focus on Surgical Management and Metastatic Cutaneous Malignancies

Salivary gland tumours are a heterogeneous group of neoplasms that predominantly affect the major salivary glands, especially the parotid, submandibular, and sublingual glands, as well as minor salivary glands in the oral cavity. In New Zealand, malignant tumours are relatively rare, accounting for 3-6% of head and neck cancers, with an incidence of approximately 1-3 cases per 100,000 population annually (Samuels et al., 2021). The majority of tumours are benign, with pleomorphic adenomas being the most common, but malignant variants, including mucoepidermoid carcinomas, adenoid cystic carcinomas, and metastatic carcinomas, pose significant management challenges.

Epidemiology of Malignancies in New Zealand

Recent data indicate that malignant salivary gland tumours comprise about 25-30% of these salivary gland neoplasms in New Zealand, often presenting at advanced stages. Notably, metastatic cutaneous malignancies—such as melanoma or squamous cell carcinoma—can spread to the salivary glands, particularly the parotid, complicating diagnosis and treatment. Metastatic cutaneous carcinomas account for a significant subset of malignant tumours involving the parotid and these originate from primary head and neck skin cancers (Ministry of Health New Zealand, 2022).

Surgical Management of Salivary Gland Tumours

Surgery remains the mainstay of treatment for both benign and malignant salivary gland tumours. The surgical approach depends on tumour location, histology, extent, and whether metastatic disease is involved.

Benign Tumours: Superficial parotidectomy is preferred for benign tumours confined to the superficial lobe. Preservation of the facial nerve is paramount, often achieved with intraoperative nerve monitoring (Wilson et al., 2020).

Malignant Tumours: For malignant salivary gland neoplasms, more extensive procedures such as total or radical parotidectomy are indicated, sometimes combined with neck dissection if lymphatic spread or metastasis is present. When metastatic cutaneous carcinoma involves the parotid, surgical excision aims to remove both the primary and metastatic disease, frequently supplemented by post operative radiotherapy (Bakewell et al., 2022).

Metastatic Cutaneous Malignancies: The management of parotid metastases originating from cutaneous melanoma or squamous cell carcinoma involves comprehensive surgically excising the involved gland and regional lymph nodes, with postoperative radiotherapy considered for high-risk cases. In melanoma and also some advanced SCC, adjuvant or even neoadjuvant immunotherapy is also indicated. Accurate diagnosis via fine-needle aspiration cytology (FNAC) and histopathology is critical to distinguish primary salivary gland malignancies from metastatic disease, guiding appropriate surgical planning, pre and post operative management (Lee et al., 2021).

Postoperative Outcomes and Follow-up

Advances in nerve monitoring and surgical techniques have improved functional outcomes, reducing facial nerve palsy rates. Long-term surveillance, including imaging and clinical assessment, is essential due to the risk of recurrence and metastasis, particularly in malignant and metastatic cases.

Conclusion

In New Zealand, surgical management of salivary gland tumours requires a tailored approach that considers the tumour histology, staging, and the potential for metastases, including from cutaneous malignancies. Multidisciplinary care and ongoing research are vital for optimizing patient outcomes.

References

- Samuels, T., et al. (2021). Epidemiology of salivary gland tumors in New Zealand. *New Zealand Journal of Medical Imaging*, 18(3), 45-50.

- Ministry of Health New Zealand. (2022). Cancer Statistics Annual Report.

- Wilson, R., et al. (2020). Surgical management of parotid tumors. *Journal of Otolaryngology*, 49(2), 123-130.

- Bakewell, S., et al. (2022). Outcomes in malignant salivary gland and metastatic cutaneous tumors. *Head & Neck Oncology*, 14(1), 34.

- Lee, W., et al. (2021). Parotid metastasis from cutaneous melanoma: Diagnostic and treatment considerations. *Australian Journal of Otolaryngology*, 4(2), 55-60.