Oral lichen planus (OLP) is a chronic T-cell mediated mucosal disease with an unknown etiology [1]. OLP affects all of the oral mucosa, involving buccal mucosa, tongue, and gingiva [1]. OLP is currently incurable, with only a limited range of symptomatic treatments available. Given the chronic and pathological nature of OLP, malignant transformation (MT) is a topic that has been discussed a lot for a long time [2-8]. The World Health Organization (WHO) classifies OLP as an oral potentially malignant disorder (OPMD) [7].

Although the gingiva is a common site of OLP involvement, the gingival lesion is known to have a relatively low incidence of MT when compared to the buccal mucosa and tongue [2]. This case report presents a case of oral squamous cell carcinoma (OSCC) arising in the gingival OLP with poor oral hygiene. The gingival swelling initially diagnosed as gingivitis or periodontitis, but ultimately it was confirmed as OSCC. The objective of this case was to identify the risk factors associated with MT of OLP in this patient and to discuss the management of patients with OLP.

This study was based on a retrospective medical record review and was approved by the Public Institutional Review Board (IRB) of the Ministry of Health and Welfare (IRB no. P01-202411-01-012). The IRB determined that obtaining informed consent from the patient was not necessary.

A 62-year-old female presented at the Department of Oral Medicine at Wonkwang University Daejeon Dental Hospital with a complaint of pain and erythema in the both buccal mucosa and the entire gingiva. The patient had been experiencing the pain for about one year. She visited other hospital, but did not receive any special treatment. The patient reported consuming alcohol on a weekly basis but denied any history of smoking. No particular medical history was identified as being associated with this symptom. The patient was taking psychiatric drugs for mental disorders and insomnia.

The intraoral clinical examination revealed erosive and atrophic lesions on the buccal mucosa and the entire gingiva (Fig. 1). The Nikolsky sign was absent in the gingiva. The simplified Debris Index was 1.83 [9], the simplified Calculus Index was 0.17 [9], and the oral disease severity scale (ODSS) was 54 (sum of site score 11, activity score 35, and pain visual analog scale [VAS] score 8) [10]. The gingiva is a thin biotype, and clinical attachment loss (CAL) was observed on the buccal side of both upper and lower posterior teeth. Cervical abrasion was present in all the posterior teeth. She exhibited a hyposalivation state and poor oral hygiene, particularly on the left lower posterior teeth. During initial visit, incisional biopsy was conducted on the right buccal mucosa. The patient had routine hematologic investigations, including anti-hepatitis C virus and anti-nuclear antibody.

The result of routine hematologic investigations was within normal limits. Patient was diagnosed with OLP according to the modified WHO diagnostic criteria of OLP (Fig. 2) [11]. The patient was informed and educated about the intractable nature of OLP. As she had poor oral hygiene ability and hyposalivation state, the antifungal agent and artificial saliva were given topically first. Two weeks later, the erosion lesion had disappeared. The ODSS was 39, and the VAS was 5. During regular check-ups for 4 months, the patient exhibited signs of inflammation, swelling, bleeding on probing (BOP), and extensive plaque accumulation in the gingival region surrounding the left lower molars, with erosion of the near left buccal mucosa. The patient exhibited an inadequate ability to perform effective oral hygiene practices. In view of the recurrent oral candidiasis and associated dryness, a course of treatment involving chlorhexidine (CHX) and topical antifungal agent was prescribed instead of topical corticosteroids. Plaque control using an ultrasonic scaler was performed at each visit. When signs of OLP were severe, tapering systemic corticosteroids were prescribed, but the patient's symptoms showed no significant improvement.

The patient was referred to a periodontist with the objective of controlling the periodontal disease (PD) in the region of the left lower molars at 4 months after initial visit. The patient exhibited buccal gingival swelling, easy BOP, probing depth of 8 mm, and radiographic bone loss (RBL) on the left lower first and second molars (Fig. 3). The periodontal treatment continued, but the gingiva on the left lower molars remained uncontrolled. Gingival swelling occurred repeatedly for 7 weeks. The patient declined further periodontal treatment and decided to visit the periodontist when discomfort occurred again. The patient did not report any pain due to OLP lesions. She declined to use topical corticosteroid and topical antifungal agent.

Four months after her last visit to the periodontist, the patient presented with pain in the gingiva of the left lower first and second molars. She said that the pain and swelling had commenced two weeks prior. The gingiva was severely swelling (Fig. 4A). She underwent incisional biopsy and the result was OSCC (Fig. 4B). The patient had undergone surgical treatment for cancer.

Ten months after, the patient presented with a complaint of pain in the right buccal mucosa (Fig. 5). The patient’s oral hygiene remained unsatisfactory, with a considerable quantity of dental plaque retained in the right upper and lower posterior molars. The necessity for optimal oral hygiene was reiterated to the patient, and plaque control was performed with an ultrasonic scaler.

OLP is a chronic T-cell autoimmune disease that can be managed effectively with regular check program. However, as OLP is classified as an OPMD, clinicians must inform patients of the potential for MT and necessity of monitor for MT. As studies have been published analyzing the MT of OLP according to the modified WHO diagnostic criteria [11], it is imperative to diagnose OLP with precision and identify MT by distinguishing between OLP and oral lichenoid lesion (OLL). The MT rate for OLP is 1.1%-1.4%, while that for OLL is significantly higher, at 1.88%-3.8% [8].

OLP is most frequently observed in the buccal mucosa, tongue, gingiva, and lips [1]. MT of OLP has been documented to occur most frequently in the tongue, followed by the buccal mucosa [2]. In general, OSCC is most prevalent in the tongue, followed by the gingiva [2].

In situations where OLP affects the gingiva, it is frequently accompanied by gingivitis or periodontitis due to inadequate plaque control. Although OLP is not a direct cause of PD, patients with gingival OLP have a higher incidence of gingival inflammation compared to patients who are free of PD [12]. In this patient, the lack of attached gingiva, narrow vestibule, and cervical abrasion contributed to the difficulty of maintaining oral hygiene. The dryness of oral mucosa facilitated plaque accumulation. The patient's oral hygiene was generally poor, particularly in the region of the left lower first and second molars, where OSCC developed. Recurrent gingival swelling was thought to be PD, which resulted in a delayed diagnosis of OSCC.

Chronic inflammation has been reported to be associated with carcinogenesis [13]. PD is a typical chronic inflammation of the oral cavity. The process of carcinogenesis can be attributed to the influence of microorganisms and their by-products, including toxins and enzymes, on the proliferation and survival of epithelial cells. Alternatively, chronic inflammation may expose epithelial cells to mutagenic substances [13]. In regard to the relationship between PD and OSCC, a systematic review and meta-analysis have demonstrated that PD is associated with OSCC (odds ratio 3.28), and particularly severe PD is associated with OSCC (odds ratio 4.23) [14]. A review of the literature reveals that increased CAL, plaque index, BOP, and RBL have been reported in patients with oral cancer and OPMD [14,15]. However, the cause-and-effect remains unclear, and further research is required to clarify it. PD can be an independent risk factor for oral cancer [16], it is therefore recommended that PD in patients with OPMD should be managed with careful attention. Furthermore, more clinical case studies related to poor oral hygiene and MT in OPMD will be needed.

OLP is also a chronic inflammatory condition in which inflammatory cytokines can promote MT in the epithelial cells [2]. In this case, the region of left lower posterior gingiva was accompanied by CAL, BOP, deep pocket depth, and RBL. The deterioration of PD and OLP is exacerbated by the creation of a vicious cycle environment, in which can be a risk factor for the MT of OLP.

It has been reported that the risk factors that influence the MT from OLP to OSCC include smoking, alcohol consumption, hepatitis C virus (HCV) infection, tongue lesions, and red lesions [8]. The literature indicates that risk factors for OSCC include smoking, alcohol consumption, and human papilloma virus (HPV) infection, and so on [17]. In this case, the patient was a non-smoker, had no HCV or HPV infection, and the lesion was not located on the tongue. Therefore, it can be postulated that poor oral hygiene may have been a contributing factor in the development of OSCC in this patient.

The management of OLP frequently entails the use of topical and systemic corticosteroids. One study has demonstrated that the use of corticosteroids has the effect of extending the interval between OLP and MT of the lesion to OSCC [18]. However, prolonged and repeated corticosteroid therapy can result in Candida infection. In this case, the patient was susceptible to oral candidiasis due to dry mouth and poor oral hygiene. Therefore, instead of using topical corticosteroids, antifungal agent and CHX were used to control the oral candidiasis. An antifungal agent was used in combination with systemic corticosteroid to prevent oral candidiasis.

It is important to control the incidence of Candida infections. An opportunistic infection, Candida represents potential contributing factor to production of carcinogen in patients with OPMD [19,20]. Candida albicans plays a role in the production of virulence factors associated with morphological phenotype changes in cell structure and genotype [20]. Additionally, Candida albicans is capable of producing carcinogenic metabolites. It directly produces a carcinogenic compound called nitrosamine and metabolizes alcohol to produce acetaldehyde, which binds to DNA and causes mutations [19,20]. This metabolism of acetaldehyde is synergized with smoking [19]. Additionally, Candida albicans induces proinflammatory cytokines, which are involved in carcinogenesis by causing chronic inflammation [19]. However, these mechanisms have yet to be clearly demonstrated in clinical studies, and further clinical studies are required.

In conclusion, as OLP is a chronic inflammatory disease, it is vital to implement a comprehensive management plan that incorporates both self-care and professional intervention. It is important to educate patients about OLP and the potential for MT, as well as the significance of oral hygiene and regular check-ups. Effective control of chronic inflammation, such as PD, and risk factors for cancer development in patients with OLP is crucial for favorable prognosis. If the intraoral environment is difficult for the patient to manage, it is important to eliminate risk factors through active professional management. A follow-up biopsy is imperative if the patient exhibits abnormal features in response to treatment or any detectable changes.

No potential conflict of interest relevant to this article was reported.

As no new data have been generated or analyzed in this study, data availability is not applicable to this article.

None.