Salivary glands are important exocrine glands and their prime function being secretion of saliva. Saliva has many protective functions. The health and function of the oral cavity depends on the secretion, composition, and flow of the saliva which inturn may be affected in various salivary gland diseases.
Saliva protects the mouth in many ways. Due to its fluid nature it flushes away the non-adherent bacteria and other debris. Apart from its role in maintaining the integrity of the tooth, it also helps in digestion, taste perception and tissue repair. By its buffering action it protects the tooth from dental caries.
Failure of salivary secretion results in dry mouth, known as xerostomia, which is distressing and leads to the imbalance of the oral ecological system. A decrease in salivary volume and altered composition leads to the development of dental caries and makes the oral soft tissues more susceptible for infections. Movements of the oral soft tissues and swallowing become difficult and painful if the mouth is dry.
Salivary glands may be affected by a number of diseases, both local and systemic.
For the sake of discussion diseases of the salivary glands are usually categorized into neoplastic and non-neoplastic.
Diagnosis of salivary gland diseases is difficult in many times. Clinicians’ diagnostic skills are often challenged in case of non-neoplastic lesions, since reactive, metabolic, autoimmune, infectious, and iatrogenic factors may produce almost similar clinical signs and symptoms. In contrast, neoplastic lesions of the salivary glands though have a similar clinical presentation, as either an asymptomatic mass or ulcer, may have varied and confusing histological patterns and their histomorphology being complex and diverse. Neoplasms of major and minor glands do differ in the frequency, rate of malignancy, and management.
Though most of the salivary gland neoplasms are arising from the epithelial parenchyma, a significant minority of them are from the non-parenchymal tissues. Even a thorough history and clinical examination may not suffice to derive a correct diagnosis. Laboratory tests, special diagnostic aids, or an incisional biopsy, coupled with the knowledge of pathology may be required for clenching the correct diagnosis.
Non-neoplastic salivary gland diseases occur throughout the world. However, certain types of diseases like sialadenitis, cysts of the parotid glands, and sialosis of metabolic etiology are seen more frequently in tropical regions when compared to rest of the world. It is not clear whether to ascribe this to a geographical or etiological predisposition.
Perception of salivary gland pathology passed through a substantial modification of terminology, histogenesis, pathogenesis, investigative procedures, and treatment modalities over a time. Till today our understanding of salivary gland pathology has not concluded, since this area is ever-changing and evolving. Here an attempt is made to present the current understanding of the diseases of the salivary glands, to be readily usable as a reference by the pathologists, physicians and surgeons.