Define Salivary Gland Tumours. Describe its classification, clinical features, investigations and management.

The Concept & a Useful Rule

Salivary gland tumours arise mostly in the parotid gland (about 80%), less often in the submandibular gland, and least in the minor salivary glands. There is a single elegant rule that organises the topic: the smaller the gland, the more likely a tumour in it is malignant. So most parotid tumours are benign (~80%), whereas about half of minor salivary gland tumours are malignant. This inverse relationship guides how worried you are about any given salivary swelling.

Classification

Clinical Features — Benign VS Malignant

A benign tumour is typically a slow-growing, painless, smooth, mobile lump — a pleomorphic adenoma classically appears as a swelling over the angle of the jaw or in the parotid tail. The features that signal malignancy are the ones to look for actively: rapid growth, pain, a hard or fixed lump, skin or deep-structure infiltration, cervical lymphadenopathy, and — most importantly for a parotid mass — a facial nerve palsy, because the facial nerve runs through the parotid and a malignant tumour infiltrates it.

Investigation

Assessment uses FNAC (to obtain a tissue diagnosis), ultrasound, and MRI (to define the extent and whether the deep lobe or facial nerve is involved). An important principle is to avoid open incisional biopsy of a parotid mass, because it risks seeding tumour and damaging the facial nerve — the diagnosis is made by needle, and the definitive excision provides the full histology.

Management

• Benign parotid tumour (pleomorphic adenoma) — superficial parotidectomy (removing the superficial lobe containing the tumour) with careful preservation of the facial nerve. Simple enucleation is avoided because the tumour has microscopic extensions through an incomplete capsule and recurs.
• Submandibular tumour — excision of the whole gland.
• Malignant tumour — radical excision (sacrificing the facial nerve only if it is directly involved), neck dissection for nodal disease, and post-operative radiotherapy.

The Facial Nerve & Parotid Anatomy

The facial nerve is the central character in parotid surgery: it enters the gland and divides it into an artificial superficial and deep lobe, its branches fanning out over the face. This is why a superficial parotidectomy — which removes the part of the gland superficial to the nerve — can treat most benign tumours while sparing facial movement, and why identifying and preserving the nerve trunk (found at landmarks such as the tragal pointer) is the crux of the operation. Deep-lobe tumours are more challenging and may present as a parapharyngeal swelling.

Complications of Parotidectomy

The complications follow the anatomy: facial nerve injury (temporary neuropraxia or permanent palsy), Frey's syndrome (gustatory sweating from aberrant nerve regeneration), a salivary fistula or sialocele, greater auricular nerve numbness of the ear lobe, and haematoma. Knowing these allows proper consent and post-operative care.

Deep-lobe & Parotid Duct

Beyond the common superficial tumour, a deep-lobe parotid tumour may grow medially into the parapharyngeal space and present as a swelling of the soft palate or tonsil pushing it towards the midline, rather than as an obvious facial lump — a presentation worth recognising. The parotid also drains via Stensen's duct, which opens opposite the second upper molar; obstruction or a tumour here can cause recurrent parotid swelling. These anatomical facts explain the varied ways parotid pathology presents and why imaging (MRI) is used to map the deep lobe before surgery.

Staging, Grading & Prognosis

Malignant salivary tumours are staged by the TNM system (size, nodal spread, metastasis) and graded histologically, both of which drive treatment intensity and prognosis. High-grade tumours (high-grade mucoepidermoid, adenoid cystic, salivary duct carcinoma) behave aggressively with nodal and distant spread, whereas low-grade tumours may be cured by surgery alone. Facial nerve involvement, extra-glandular extension and positive nodes all worsen the outlook. This is why the pre-operative assessment (FNAC grade, MRI extent, nodal status) matters so much: it separates the patient who needs only a superficial parotidectomy from the one who needs radical surgery, neck dissection and radiotherapy.

A Clinical Summary

In summary, the assessment of a salivary swelling asks three questions: which gland, benign or malignant, and (for the parotid) is the facial nerve involved? A slow, painless, mobile parotid lump with an intact nerve is very likely a pleomorphic adenoma treated by superficial parotidectomy; pain, fixation, rapid growth, nodes or nerve palsy signal malignancy needing radical surgery and radiotherapy. This simple triad — gland, behaviour, nerve — organises the whole topic for the viva.

• Parotid ~80% of tumours and ~80% benign; the smaller the gland, the higher the malignancy risk.
• Facial nerve palsy + parotid mass = malignancy until proven otherwise.
• Pleomorphic adenoma → superficial parotidectomy (not enucleation); avoid open biopsy of the parotid.

The smaller the gland, the greater the chance of malignancy.

• Most salivary tumours are in the parotid (~80%) and benign; the smaller the gland, the higher the malignancy risk.
• Benign: pleomorphic adenoma (commonest, recurs if enucleated), Warthin's tumour (older men, bilateral, cystic). Malignant: mucoepidermoid (commonest malignant), adenoid cystic (perineural, lung mets).
• Malignant features: rapid growth, pain, hard/fixed, skin/node involvement, and facial nerve palsy (parotid).
• Investigate with FNAC, ultrasound, MRI; avoid open incisional biopsy of the parotid.
• Pleomorphic adenoma → superficial parotidectomy preserving the facial nerve; malignant → radical excision ± nerve sacrifice + neck dissection + radiotherapy.