2. A sweaty face

A 77-year-old female complained of sweating from her face anterio-inferiorly to her right ear for 5 years. One year previously, the patient developed transient anosmia, but ENT and MRI examinations revealed no pathology, and the anosmia cleared, though the sweating increased. The history revealed a right partial parotidectomy for a mixed salivary tumour 14 years previously.

Examination revealed no fluid, nor signs of fistula or cutaneous infection but, when the patient drank citrus juices, her right auricular and parotid area became sweaty (Figure 1a). Fluid was also appearing at the pre-auricular area during mastication.

(b) Frey syndrome: this is characterized by unilateral sweating and flushing of facial skin in the area of the parotid gland during mastication. Frey syndrome (Baillarger, Dupuy, Gustatory or Auriculotemporal syndrome) arises after parotidectomy or sympathectomy, as a result of severance and inappropriate nerve regeneration, the parasympathetic fibres switching to severed postganglionic sympathetic fibres which innervate facial sweat glands, causing ‘gustatory sweating’ (sweating in anticipation of food), instead of the normal salivatory response. The starch-iodine test detects hyperhidrosis (Figure 1b). Tincture of iodine is applied and left for 10 minutes to dry out, and then a layer of starch is applied. The patient is given lemon juice and the area that sweats turns blue or violet, as a result of the interaction of starch and iodine catalysed by the moisture. Frey syndrome was suspected and confirmed by the starch iodine test. It may respond to hyoscine therapy.