Malignant transformation of a clinically and histologically healed lichenoid lesion after amalgam removal: A case report and literature review

Lichenoid contact lesions (LCLs) frequently develop in close contact with amalgam restorations and may regress after amalgam removal, especially when patch testing is positive to amalgam components. However, established criteria to define true LCLs healing are missing and clinical disappearance of the lesion may not always correspond to a complete regression of histological lichenoid tissue reaction. Similarly to other lichenoid lesions of the oral cavity, LCLs are included among potentially malignant disorders although its malignant transformation remains controversial. As a result, with no clear indications for neoplastic risk assessment, the management of patients with LCLs may be challenging. The present report describes the unusual case of an oral squamous cell carcinoma (OSCC) arising in the same site where 6 years before an amalgam-associated LCL had clinically and histologically healed after restoration replacement. A review of the few literature reports of amalgam-associated LCLs developing to OSCC is also provided.