The association between skin allergy testing and oral squamous cell carcinoma in oral lichen planus: A retrospective cohort study

Abstract

There is a reported association between oral contact allergy and oral lichen planus (OLP). Likewise oral squamous cell carcinoma (oSCC) is associated with OLP. However, risk factors for malignant transformation are unclear and it is not known if oral contact allergy impacts OLP disease severity or subsequent risk of oral squamous cell carcinoma (oSCC). In this study, we aimed to assess the association between allergy testing positivity and oSCC in OLP. We also assessed oSCC prevalence in OLP, allergen prevalence in OLP, and associations between allergy testing and OLP phenotype. To do this, we performed a retrospective cohort evaluation investigating the association between allergy testing positivity, clinical and demographic factors, and the odds of oSCC. Patients were seen at the University of Utah from 2015–2022. The rates of oSCC and allergy testing (patch + scratch testing) results were summarized descriptively and associations between oSCC, disease phenotypes, and allergy testing results were assessed using univariable and multivariable logistic regression. Patients were selected if they had a confirmed diagnosis of oral lichen planus as determined by a dermatologist or a dentist specializing in inflammatory oral disease. Allergy testing was performed by two specialized dermatologists. oSCC diagnosis was identified via chart review and were supported by histologic data. All data was collected via retrospective chart review. Among 587 OLP patients identified, 133 were allergy tested and 77.4% were positive. Of those with a positive allergy test, 10 (25.6%) developed oSCC compared with 2 (5.1%) of patients with a negative allergy test. There was insufficient evidence to support an association between allergy positivity and oSCC (OR = 1.55, 95% CI 0.76–3.15). Of the OLP disease characteristics tracked, only OLP involving the gingiva was associated with positive allergy testing (OR = 2.54,1.11–5.81). Likewise, a higher percent of symptomatic visits was the only clinical factor associated with oSCC (median 87.5% vs 66.7%, p = 0.03). These data suggest that allergy test positivity may not be associated with oSCC. However, it was associated with more pervasive symptomatology, suggesting a possible association with more severe or recalcitrant disease.