Salivary gland diseases are fundamentally divided into two main categories: neoplastic (tumoral) and non-neoplastic (non-tumoral) diseases.

Neoplastic salivary gland diseases typically manifest as fixed and progressively enlarging masses or swellings in the affected gland region. These can be benign or malignant tumors.

Non-neoplastic salivary gland diseases, on the other hand, present with a wider range of symptoms. These symptoms may include recurrent, sometimes spontaneously resolving painful swellings, excessive salivation (hypersalivation), or dry mouth (xerostomia). Examples include the following conditions:
* Acute salivary gland infection
* Recurrent salivary gland infection
* Salivary gland stones (sialolithiasis)
* Salivary gland duct stricture or adhesion (sialodochiectasis, stenosis)
* Childhood recurrent parotitis (Juvenile Recurrent Parotitis)
* Sjögren's syndrome
* Recurrent salivary gland infections after radioactive iodine therapy
* Excessive salivation (hypersalivation)
* Dry mouth (xerostomia)