Oral Lichen Planus Pemphigoides: Three Cases of a Rare Entity

Lichen Planus Pemphigoides Associated With PD-1 and PD-L1 Inhibitors: A Case Series and Review of the Literature

ABSTRACT

Immune checkpoint inhibitors are increasingly being used in the treatment of various solid organ and hematologic malignancies. Dermatologic toxicities associated with programmed cell death protein-1 (PD-1) and programmed death ligand-1 (PD-L1) therapy have been widely reported in the literature. It is important for clinicians to be aware of these toxicities to ensure prompt recognition and treatment. Herein, we present the clinical, histopathologic, and immunofluorescence findings of 3 patients diagnosed with lichen planus pemphigoides (LPP) after treatment with anti-PD-1 inhibitors. We also reviewed the literature and summarize 7 previously reported cases of LPP associated with anti-PD-1 and anti-PD-L1 inhibitors. LPP was diagnosed at a median time of 24.4 weeks (range: 4-78 weeks) after initiation of immunotherapy. Clinical findings included papules, plaques, erosions, vesicles, and bullae on the trunk and extremities. Oral involvement was present in half the cases. Histopathologic features of immunotherapy-induced LPP included lichenoid or vacuolar interface dermatitis, the presence of eosinophils, and subepidermal bullae. Direct immunofluorescence demonstrated linear deposition of immunoglobulin G (IgG) or C3. Indirect immunofluorescence demonstrated linear IgG along basement membrane zone on monkey esophagus in 2 cases and linear IgG on the epidermal side of salt split skin in 3 cases. Serum anti-BP180 was elevated in all cases in which enzyme-linked immunosorbent assay was performed.

Challenges and pitfalls between lichen planus pemphigoides and bullous lichen planus

Lichen planus pemphigoides (LPP) and bullous lichen planus (BLP) are rare dermatoses, which are characterised by blisters and lichenoid lesions. Their clinical presentation is heterogenous, displaying overlapping features or mimicking other dermatological diseases. Therefore, diagnosis can often be challenging, requiring a thorough dermatological examination along with distinctive histological and immunopathological characteristics. Lichenoid degeneration of the basal epidermis exposes various antigens of the dermal-epidermal junction in LPP, resulting in the breakdown of immune tolerance, hence, the production of autoantibodies against type XVII collagen. Conversely, no pathogenic autoantibodies are detected in BLP. However, some cases of mucosal lichen planus might display immunopathological features suggestive of autoimmune blistering diseases. Therefore, a better understanding of the pathophysiology of these two distinct dermatoses is imperative. The aim of this review was to provide a summary of the current knowledge on the clinical hallmarks, diagnosis and available therapeutic options in LPP and BLP.

Coexistence of oral mucous membrane pemphigoid and lichenoid drug reaction: a case of toripalimab-triggered and pembrolizumab-aggravated oral adverse events

Toripalimab and pembrolizumab belong to anti-programmed death receptor-1 monoclonal antibodies for the treatment of various cancers. Anti-programmed death receptor-1 therapy can cause mucocutaneous adverse events. Here, we report the first case, to our knowledge, of oral mucous membrane pemphigoid and lichenoid reaction triggered by toripalimab and aggravated by switching to pembrolizumab. Mucous membrane pemphigoid was a definite diagnosis, whereas lichenoid reaction was a clinical diagnosis without pathologic evidence. Although discontinuation of the culprit drugs achieved clinical resolution in most reported cases, multiple studies demonstrated statistically significant associations between the development of dermatologic adverse events and superior clinical outcomes. Thus, more studies are needed to find satisfactory measures in terms of both cancer control and avoidance of severe adverse events.