The best choice is noncontrast CT of the neck. These studies ane inexpensive and easy to obtain. They are the best way to look for stones, which are always calcified, and to screen for sialadenosis (fatty infiltration of the glands, which can be due to chronic use of steroids or metabolic problems.
In this case, the CT showed parotid enlargement, but no stones or parenchymal abnormalities. The patient also showed several inflammatory markers (CRP 5 mg/L, increased serum beta2 microglobulin) and low C3 and C4.
Diagnosis: Inflammatory sialadenitis
Inflammatory sialadenitis is by far the most common cause of intermittent or chronic salivary gland swelling. It is associated with polyclonal B cell activation or elevation of acute phase reactants. The condition is steroid-responsive (e.g. methylprednisolone(Drug information on methylprednisolone)), but tends to recur when steroids are discontinued. Options for long-term therapy include hydroxychloroquine(Drug information on hydroxychloroquine), methotretaxe, and in the worst cases, IV rituxumab.
This patient was treated with hydroxychloroquine and pilocarpine(Drug information on pilocarpine), but the left parotid gland did not improve. A biopsy of the left parotid tail four months later showed non-Hodgkins B cell lymphoma, which was graded as Stage I and treated with rituximab(Drug information on rituximab) after referral to oncology. Five years later the patient is doing well.
Click here for key points about parotid gland swelling in Sjögren syndrome.