The most common malignant tumour of salivary glands in people of all ages.
An unusual pattern of incidence typifies this tumour. The average age of diagnosis is 45, with less diagnoses at the extremes of age. It can arise from any of the salivary gland sites; about half arise in the major glands.
Incidence, age of onset, gender, geography
Aetiology and Pathogenesis
No specific aetiologies have been identified other than the common salivary gland causes.
Tumours may be locally invasive but are often limited by bony boundaries. They spread to local lymph nodes depending on the site of origin. Metastatic spread occurs to the usual sites (bone, brain, lung, liver).
The classical presentation is of a painless lump in the parotid region or within the oral mucosa. Local invasion can cause cranial nerve palsies, pain or bleeding.
Macroscopically the tumours are light coloured with either infiltrative or well defined borders. Cystic areas may be present.
Microscopically the tumour is comprised of three cell types:
- An epidermoid squamous component
- A mucous producing adenocarcinoma-like component
- An intermediate component
The architecture of these components is variable; usually there is formation of cysts mixed with solid regions.