Malignant Potential of Oral Lichen Planus/Lichenoid Lesions

Oral Lichen Planus and Oral Lichenoid Lesions

Oral lichen planus (OLP) affects 0.22%-5% of the population worldwide and is considered to be a relatively common, chronic, oral mucocutaneous inflammatory disease that is poorly understood.^[1,2,3] T lymphocytes are thought to mediate a reaction to an exogenous antigen or an autoantigen expressed by epithelial cells.^[4]

The various clinical forms of OLP include reticular, plaque-like, erosive and bullous multifocal lesions. Controversy regarding the malignant potential of OLP has existed since the mid-1920s.^[3]

OLP is also well known for its clinical and histopathologic diagnostic challenges, especially because of the overlapping characteristics between OLP and oral lichenoid lesions (OLLs). OLLs have a similar appearance, but are mostly considered to be clinically unifocal.

OLLs have a multitude of potential etiologies, including various medications (eg, nonsteroidal anti-inflammatory drugs, antihypertensives, antimalarials) and topical agents (eg, dental materials, cinnamon, flavoring agents).^[2] Histologic overlap between OLP/OLLs and other diseases, such as oral lupus erythematosus, oral dysplasia, proliferative verrucous leukoplakia, and oral squamous cell carcinoma (OSCC), fosters diagnostic confusion.^[2,3]

The World Health Organization developed clinical and histopathologic diagnostic criteria for OLP in the late 1970s, and modified histologic criteria are currently supported by the American Academy of Oral and Maxillofacial Pathology.^[3] The Academy emphasizes clinicopathologic correlation for the diagnosis of OLP.^[3]

Quantification of the malignant potential of OLP/OLLs has been complicated, owing to these various diagnostic issues. Even with prior analyses reporting OLP malignant transformation rates (0.4%-12.5%) and the World Health Organization designating OLP as a premalignant condition in 2005, controversy regarding its malignant potential persists.

Malignant Potential of Oral Lichen Planus and Oral Lichenoid Lesions

In an April 2017 meta-analysis of observational studies published in Oral Oncology, Aghbari and colleagues^[1] sought to evaluate the malignant potential of OLP and OLLs. In the end, 57 studies were eligible for the analysis. Data on 19,676 OLP and 419 OLL cases were included.

Overall, when these cases were pooled, the proportion of patients with OLP who developed OSCC was 1.1%. The rate of malignant transformation for the OLL cases was 2.5%.^[1] These authors tried to mitigate diagnostic confusion by performing a subgroup analysis of the studies that used the modified WHO 2003 criteria, and by using independent data sets. (The authors also investigated the association between OLP malignant transformation and smoking, alcohol intake, and hepatitis C.)

Viewpoint

Oral healthcare providers must be aware of oral diseases with increased malignant potential. This meta-analysis provides new data that continues to support the concept that OLP and OLLs are associated with a small, yet measurable, increased risk (1.1%) of developing OSCC.

As healthcare providers increase their knowledge, awareness, and clinical skills surrounding oral cancer and lesion screening, it is paramount for providers to also know the latest data regarding the malignant potential of OLP/OLLs. Once a provider has a firm grasp on the disease process, diagnostic challenges, and malignant potential, the clinician will most certainly feel more confident in counseling patients with OLP/OLLs about these important issues.

All oral healthcare providers should be on alert for oral cancer and oral lesions, and firmly recommend baseline biopsy to help rule out neoplasia/dysplasia, while establishing a proper diagnosis and management plan. When indolent and/or suspicious lesions are seen during subsequent follow-up visits, providers should strongly consider and recommend an additional biopsy procedure.

Making an accurate oral diagnosis is the foundation for properly establishing and managing a particular patient's overall malignant risk. As clinicians, we also want to formulate a long-term clinical follow-up strategy for these patients. Although there is no agreed-upon number of follow-up visits, Aghbari and colleagues recommend two clinical visits annually.^[1] Regular follow-up of patients with OLP/OLL provides opportunities to detect oral cancers early.

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