A dentist noticed this white patch during a routine dental examination. The patient was sent to a hospital unit as a routine referral for an opinion on its nature. The white patch is unilateral has a lichenoid appearance and is closely associated with an amalgam restoration, present in the lower second molar tooth. Following investigation this was confirmed as an oral lichenoid reaction to a dental restoration.
Notes: This white patch needs to be investigated by biopsy and patch testing. The microscopic features that distinguish a lichenoid reaction from lichen planus are not well characterised. Patch testing revealed that the patient reacted positive to amalgam 5% and ammoniated mercury 1%. Based on the clinical appearance, its unilateral nature , close association with an amalgam restoration and the patch test results this was confirmed as a lichenoid reaction. It was appropriate for the dentist to refer this patient as a routine referral as there are no suspicious features. Some lichenoid lesions have been reported to transform to cancer and should therefore be followed up regularly. The removal of the cause may allow resolution of this localised reaction.
[Photo supplied by Prof Warnakulasuriya]