Head & Neck
Tumours of the Parotid & Submandibular Glands
Tumours in the parotid salivary gland typically appear as a lump near or below the ear. Parotid lumps are abnormal swellings or growths that can develop in the parotid glands, affecting both adults and children. While 80% of these lumps are benign, we often recommend their removal because they typically continue to grow and can become visually unappealing. Over time, a benign lump may also potentially transform into a malignant one.
Furthermore, larger lumps pose greater challenges for removal, which underscores the importance of prompt surgical intervention. Until a lump is surgically removed and examined, there is always some uncertainty about its exact cause, which adds to the rationale for early intervention.
The most common benign tumors are pleomorphic adenoma and Warthin's tumour with about 5% possibility of the adenomas transforming into cancer. Epidemiological data show Warthin's tumours are predominantly found in male smokers in their 70’s.
Approximately 15% of the parotid gland tumors are malignant. Signs of a malignant tumour include facial weakness or paralysis and enlarged lymph nodes in the neck. These tumours can sometimes cause pain or grow rapidly. Common malignant tumours in the parotid gland include squamous cell carcinoma (SCC) that has spread from the skin; mucoepidermoid carcinoma; and adenoid cystic carcinoma.
Tumours of the submandibular salivary gland are less frequent with masses typically appearing as firm to hard, within the gland. They are usually mobile. About one-third of these masses could become malignant when they become fixed and involve nerves (lingual, marginal branch of facial, and hypoglossal). Skin cancers and melanoma can also spread to lymph nodes in this region. However, unlike the parotid gland where lymph nodes are within the gland itself, in this region, they are attached to the fascia around the gland. These lymph nodes are commonly associated with the facial artery.
Even rarer are tumors of the sublingual salivary gland, and approximately half are malignant. They manifest as a firm mass located in the floor of the mouth and frequently affect the lingual nerve, leading to numbness in the tongue and floor of the mouth. Spread to the neck is rare.
Minor salivary gland tumours are less common but more likely to be malignant. These lumps appear as submucosal masses on the oral or nasal mucosa. They are most frequently found on the palate, lip, tongue, and floor of the mouth.
Investigation & Diagnosis
Clinical assessment plays a crucial role in diagnosing salivary gland masses. To determine whether a lump in the salivary gland (parotid or submandibular) is benign or cancerous, a thorough examination, including flexible endoscopy, is conducted. This involves numbing the inside of the nose and inserting a small, flexible camera to evaluate the nose, throat, and voice box. An ultrasound scan may also be performed.
Ultrasound is valuable for assessing superficial parotid lesions, which are the most common, as well as of the submandibular gland. It helps determine if a lesion is located within the gland and distinguishes between cystic and solid lesions. Ultrasound, CT / MRI Sialogram are other imaging techniques that may be used for diagnosis.
Treatment
Surgery is often recommended for most tumours, including benign ones like pleomorphic adenomas, due to the risk of transformation into cancer, over time. The most critical investigation varies depending on the tumour's location. Open biopsy is utilised for minor salivary gland and sublingual tumours. It may be incisional or excisional depending on the lesion's size. This method provides accurate assessment as it allows examination of tissue architecture in addition to cells.
Treatment for parotid tumours typically involves surgical removal (parotidectomy).
For patients with malignant tumours, medical history and examination findings are presented and discussed. All diagnostic imaging (CT/ MRI scans) results are reviewed, and treatment recommendations are made. High-grade malignant tumours may require a neck dissection procedure; submandibular gland tumours are treated with excision of the gland. Some patients with malignant tumours may undergo post-surgery radiotherapy.
Some cases may require a complex intervention including resection of skin, facial nerve or its branches, or part of the ear; and in high grade tumours, may need a neck dissection, as well. Although benign submandibular tumours can be managed by submandibular gland excision, malignant tumours may need additional neck dissection. In patients where the tumour involves facial nerve branches or the main trunk, facial reanimation procedures such as static/dynamic reanimation, gold weights + tarsorrhaphy, browlift, fascia lata slings, cable nerve graft neurorrhaphy, masseteric nerve transfer with cross facial nerve grafting +/- babysitter neurorrhaphy – hypoglossal - facial nerve neurorrhaphy may be performed. Additionally, free muscle transfer such as gracilis flap, and ALT neuro myofascial transfer among others may be undertaken.
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