Diseases of the Salivary Glands

An overarching framework for the range of conditions affecting the major (parotid, submandibular, sublingual) and minor salivary glands. This entry provides the shared anatomical and diagnostic framework underpinning the more detailed, individual condition entries addressed throughout this Atlas.

The conditions covered are:

• obstructive disease (sialolithiasis)
• infective and inflammatory disease (acute bacterial sialadenitis, parotitis, and sialadenosis)
• neoplastic disease (benign and malignant salivary gland tumours)

Anatomy and general principles

• The parotid gland, the largest major salivary gland, is predominantly serous in secretory character. It drains via Stensen duct opposite the second upper molar tooth.
• The facial nerve courses directly through the substance of the gland, dividing it into superficial and deep lobes.
• This is a critical anatomical relationship, directly relevant to both the presentation and surgical management of parotid disease, particularly malignancy, given the risk of facial nerve involvement. In benign disease, the surgical risk is iatrogenic facial nerve injury during gland surgery.
• The submandibular gland is predominantly mixed seromucous in secretory character, with a relatively higher mucous content compared with the parotid gland. It drains via Wharton duct into the floor of the mouth.
• Its more viscous, mucous-rich secretion and the relatively long, upward-coursing duct together account for its substantially higher propensity for sialolithiasis compared with the other major salivary glands, addressed under that specific condition.
• The general principle is that a discrete parotid mass is more likely benign, while a discrete submandibular gland mass carries a proportionally higher likelihood of malignancy. This reflects the differing relative proportions of benign and malignant tumour types arising within each specific gland. It is an important, general epidemiological principle informing clinical risk assessment.

• Diffuse, bilateral salivary gland swelling generally reflects a systemic or diffuse process (including sialadenosis, viral parotitis, or, in the specific context of dry mouth and eye symptoms, Sjögren syndrome).
• Unilateral, focal swelling more typically reflects a localised, structural process (obstruction from sialolithiasis, a discrete neoplasm, or a localised inflammatory or infective process).
• Pain, particularly if related to eating, together with recurrent, episodic swelling, supports an obstructive, calculus-related process. Eating-related pain reflects the physiological, meal-stimulated increase in salivary flow provoking pain in the context of ductal obstruction.
• A slowly progressive, painless mass more typically suggests an underlying neoplastic process.
• Associated facial nerve weakness (in the parotid gland specifically) is a critical clinical feature strongly suggestive of malignancy where present.
• Fever, systemic upset, and marked tenderness typically accompany an acute infective or inflammatory process.

• Ultrasound is the standard, first line imaging investigation for any salivary gland swelling or mass. It offers good characterisation of cystic versus solid lesions, ductal dilation suggestive of obstruction, and guidance for fine needle aspiration where a discrete mass is identified.
• Fine needle aspiration cytology, ideally ultrasound guided, is an important, standard component of the assessment of any discrete salivary gland mass, supporting preoperative risk stratification and surgical planning.
• Fine needle aspiration cytology has recognised limitations in fully distinguishing between certain specific benign and low grade malignant tumour subtypes. Definitive diagnosis therefore frequently rests on formal histopathological assessment of the surgically excised specimen.
• Magnetic resonance imaging offers superior soft tissue characterisation for more detailed preoperative assessment, particularly relevant for larger or deep lobe parotid lesions, or where there is any clinical suspicion of malignancy with potential facial nerve or adjacent structure involvement.

• Management is directed entirely according to the specific underlying diagnosis established. It follows the detailed principles addressed under the individual conditions throughout this Atlas (sialolithiasis, acute bacterial sialadenitis, parotitis, sialadenosis, ranula, and benign and malignant salivary gland tumours).
• This overarching entry serves as the anatomical and diagnostic framework rather than prescribing a specific, standalone treatment approach in itself.
• Referral to a specialist head and neck or maxillofacial surgical service is generally appropriate for any persistent, undiagnosed salivary gland mass, or for any salivary gland swelling with features raising concern for malignancy.
• This reflects the importance of full, structured assessment and appropriately specialist-led surgical management where indicated.