You are asked to see a 32-year-old man who recently underwent surgical removal of a left parotid gland tumor. Since surgery, he has noted sweating over the left parotid area following ingestion of spicy foods or lemons. What is your diagnosis and what is the pathophysiology of this disorder?.
DIAGNOSIS: Frey's syndrome. A somewhat rare complication of parotid injury (usually surgical) caused by the aberrant regeneration of the auriculotemporal nerve, a branch of cranial nerve V. This nerve normally supplies the parotid and sweat glands of the scalp, but is re-routed to sweat glands in the cheek. Ingestion of food (particularly spicy food) stimulates these glands, hence the "gustatory sweating" seen in the second image. Minor's test reveals the affected area by painting the skin with a solution of iodine, ricine oil, and alcohol, daubing the dried skin with potato starch, and having the patient chew a piece of bread (thanks to Pooja Jagadish for this factoid). Gustatory sweating may be a prominent symptom in diabetics suffering from autonomic nervous system dysfunction, and can occur in normal individuals upon ingestion of very spicy foods.