Oral lichen planus is a chronic inflammatory disease of unknown etiology.Malignant transformation of oral lichen planus is a controversial subject. A case of malignant transformation of lichen planus of the tongue was reported and the literature was reviewed.
The patient was a 48-year old woman referred to our hospital with a chief complaint of contact pain of the lateral border of the tongue.Clinical and histopathological examination revealed lichen planus, with no malignancy signs. Despite treatment with corticosteroids locally and systemically and Etretinate, she showed little if any improvement and the lesion eventually developed to squamous cell carcinoma 5 years after the lichen planus diagnosis.
The patient has been in good condition with no recurrence for 1 year and 10 months after removal of the tumor with co2 laser.
We analized the data from the literature of malignant transformation of lichen planus.
The following results were obtained.
1) Transformation rate in foreign literature ranged from 0% to 10%, with an average of 3%, but only a single case in Japan.
2) Of the 33 cases, carcinoma arose in 17 the erosive type, in 7 plaque type, and in 5 reticular type.
3) The duration of oral lichen planus before transformation was 1.5 years to 40 years, with an average of approximately 10 years.
More extensive investigations are needed to ascetain whether lichen planus is to be regarded as a precancerous condition.
