Sialadenosis: insulin resistance?
QCould bilateral painless parotid enlargement be a manifestation of 'insulin resistance syndrome'? There are six men in our practice with this condition and all have raised blood pressure, cholesterol, triglyceride and impaired glucose tolerance. Known causes of bilateral parotid enlargement mumps, Sjögren's syndrome and sarcoidosis have been excluded.
AChronic, painless bilateral parotid gland enlargement or sialadenosis is an uncommon cause for an ENT consultation. The textbook causes include sarcoidosis and Sjögren's syndrome; one could add bilateral Warthin's tumours (adenolymphoma) to the differential diagnosis because these are common tumours of the parotid gland.
It would be appropriate to request angiotensin converting enzyme and salivary gland autoantibody testing, but fine needle cytology or even open biopsy may be necessary to obtain a diagnosis.
I have seen several cases of bilateral salivary gland enlargement associated with diabetes, the histological finding in each case being fatty infiltration around normal parotid tissue, as distinct from an intraparotid lipoma. There are published reports of this and it is variously stated that 24-25 per cent of patients with overt or latent diabetes have bilateral asymptomatic enlargement of the parotid glands.
Sialadenosis due to fatty infiltration is also reported in alcohol abuse and I would imagine the mechanism is the same as in diabetes with a disturbance of fat metabolism, in this case secondary to liver dysfunction.
I understand that insulin resistance syndrome is likely to be a disorder of fat metabolism and I would therefore concur with the stated diagnosis.
Patients with chronic bilateral painless parotid gland enlargement should undergo screening tests for diabetes at an early stage in their investigation.
Michael Frampton is consultant in ENT at Bedford Hospital, Bedford