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.

Oral field cancerization: history and future perspectives.

Notwithstanding extended surgical approaches or adjuvant chemoradiotherapy, the development of multiple neoplastic lesions arising in the oral cavity after treatment still represents a critical clinical challenge in the management of patients with oral squamous cell carcinoma. Such clinical behavior of oral squamous cell carcinoma is nowadays better known as "field" cancerization effect as suggested by Slaughter, the author that for the first time tried to describe it in a scientific paper. Field cancerization is now widely accepted not only in head and neck oncology but also in other anatomical districts as well as in different types of epithelial neoplasia. A brief history of the theory of field cancerization is here proposed and future perspectives deriving from new molecular techniques are discussed.

Clonal analysis as a prognostic factor in multiple oral squamous cell carcinoma.

OBJECTIVES: A novel classification based on molecular methods to assess clonality defines three types of secondary oral squamous cell carcinoma (OSCC): second primary tumour (SPT) independent from the index tumour, local recurrence (LR), clonally related to the primary tumour, and second field tumour (SFT), derived from the same genetically altered mucosal field as the primary tumour. The present study applied mtDNA analysis in a group of patients experiencing a second loco-regional neoplastic manifestation. The purpose was to differentiate secondary tumours into LRs, SPTs and SFTs and evaluate the prognostic impact in terms of survival rate. MATERIAL AND METHODS: The study population comprised 23 patients who experienced a second neoplastic lesion after a surgical resection of primary OSCC. mtDNA D-loop analysis was applied in paired neoplastic lesions and in clinically and histologically normal mucosa. On the basis of mtDNA results, the second OSCC was classified as LR or SPT or SFT. Disease-free survival was defined as the duration between the appearance of the second neoplastic lesion and death of disease, or last follow-up visit. RESULTS: Seven secondary tumours were classified as LR, 12 as SFT, 4 as SPT. An altered mucosal field proved a variable significantly related to a better survival rate (p<0.05); 2/12 (16.6%) SFT events failed as compared to 5/7 LRs (71.4%) and 3/4 SPTs (75%). CONCLUSION: mtDNA analysis may be considered a useful tool to differentiate secondary tumours and might influence the choice of the most appropriate treatment in patients with multiple OSCCs.