Oral Bullous Lichen Planus (BLP) and Oral Lichen Planus Pemphigoides: A Diagnostic Dilemma

Introduction

Bullous Lichen Planus (BLP) and Lichen Planus Pemphigoides (LPP), both very rare presentations of oral mucosal diseases can be difficult to diagnose. Whereas BLP is the rarest variant of lichen planus, LPP is the rarest variant of bullous pemphigoid. The oral presentation of BLP and LPP often are similar, leading to misdiagnosis and diagnostic delay. BLP and LPP present similarly clinically with bullae and background white striations. Clinical history is important as LPP usually evolves from a long-standing history of reticular oral lichen planus however, historical records may not always be available and oftentimes patients present for the first time to an oral medicine specialist with concurrent lichenoid changes and bullae complicating the diagnosis. The clinical and histopathologic features of both oral BLP and oral LPP are indistinguishable and therefore additional immunofluorescence studies are needed to differentiate the two.

Case Report

Our case report demonstrated histopathological findings of an intact bulla with adjacent lichenoid mucositis. Additional direct immunofluorescence (DIF) studies did not show linear IgG, IgA, IgM, or C3 deposition at the basement membrane zone therefore confirming a diagnosis of oral BLP. This case report highlights the importance of DIF studies in differentiating between these two rare entities. An accurate diagnosis is critical due to the significance in prognosis between the two conditions, notably, oral LPP is considered a systemic autoimmune disease that may evolve with progressive scarring involving the conjunctivae resulting in blindness. Additionally, scarring of other mucosal sites can lead to respiratory distress and dysphagia.

Conclusion

In conclusion, oral LPP is underdiagnosed due to the lack of prescribed immunofluorescence studies in cases that may appear similar to oral LPP such as this case report of oral BLP