Submandibular Gland Tumours

The submandibular gland lies under the lower jawbone, in the upper part of the neck, and produces a substantial share of the saliva. Tumours of this gland are less common than those of the parotid gland; however, because the likelihood of malignancy is somewhat higher, every mass under the jaw is assessed carefully. A large proportion of swellings under the jaw are not tumours at all but are due to salivary stones or inflammation.

The submandibular gland and neighbouring structures

The gland empties saliva into the mouth through a duct (Wharton’s duct) that opens on the floor of the mouth. Around it lie the branch of the facial nerve that moves the lower lip (marginal mandibular branch), the nerves that supply sensation and movement to the tongue, and the lymph nodes of the neck. Protecting these structures is essential when planning treatment.

Symptoms

• A painless, slowly growing, firm lump under the jaw
• A swelling that enlarges during meals and then subsides (this suggests a salivary stone rather than a tumour)
• Pain, redness of the skin or the feeling of a mass pushing into the mouth
• Numbness of the tongue, difficulty moving the tongue or weakness of the lower lip

Swellings that come and go in relation to meals are usually due to a blocked duct. A mass that is constantly present and slowly growing, on the other hand, should be evaluated for a tumour.

Diagnosis

During the examination, the mass is assessed with both hands, from the neck and from inside the mouth. Ultrasound shows whether the mass lies within the gland or in a neighbouring lymph node and whether a stone is present. Fine-needle aspiration biopsy provides preliminary information about the nature of the tumour. When malignancy is suspected or the mass is large, magnetic resonance imaging (MRI) or computed tomography (CT) is used to assess its extent.

Treatment

The treatment of submandibular gland tumours is removal of the whole gland together with the tumour (submandibular gland excision). The incision is made a few fingerbreadths below the edge of the jaw, following a neck crease; the nerve branch to the lower lip and the nerves of the tongue are protected. In malignant tumours, the surrounding lymph nodes may be removed together with the gland; radiotherapy may be added after surgery depending on the pathology result.

After surgery

Most people return to a normal diet shortly after surgery. Temporary weakness at the corner of the lower lip, numbness under the jaw and mild swelling may occur; these usually subside within weeks. Because the remaining salivary glands take over the function, noticeable dry mouth is not expected. The scar fades with time and blends into the neck crease.

When should you see a doctor?

If you notice a lump under the jaw that has not gone away for a few weeks, a mass that is growing or hardening, numbness of the tongue or weakness of the lip, it is advisable to seek an evaluation.