[Intertriginous vesicle and pustule development in a 36-year old]

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.

Lichen Planus Pemphigoides: From Lichenoid Inflammation to Autoantibody-Mediated Blistering

Lichen planus pemphigoides (LPP) is a very rare autoimmune sub-epidermal blistering disease associated with lichenoid skin changes. Initially thought to be a mere variant of more common inflammatory dermatoses, particularly Bullous Pemphigoid (BP) or Lichen Planus (LP), a growing body of evidence suggests that it is a disease entity in its own right. In common with a range of autoimmune blistering diseases, including BP, pemphigoid gestationis (PG), mucous membrane pemphigoid (MMP) and linear IgA dermatosis (LAD), a key feature of the disease is the development of autoantibodies against type XVII collagen (COL17). However, accurately establishing the diagnosis is dependent on a careful correlation between the clinical, histological and immunological features of the disease. Therefore, we present an up to date summary of the epidemiology and etiopathogenesis of LPP, before illustrating the predisposing and precipitating factors implicated in the development of the disease. In addition to a selective literature search, we compare reports of potential drug-induced cases of LPP with pharmacovigilance data available via OpenVigil. We subsequently outline the cardinal clinical features, important differential diagnoses and current treatment options. We conclude by demonstrating that an improved understanding of LPP may not only lead to the development of novel treatment strategies for the disease itself, but may also shed new light on the pathophysiology of more common and treatment-refractory autoimmune blistering diseases.

[Relevance of histological examination in the diagnosis of autoimmune bullous dermatoses]

The histopathological picture of many autoimmune bullous dermatoses is considered to be relatively characteristic. However, different entities may show similar histological findings. In addition, the picture depends on both the stage of the disease and prior treatment. Autoimmune bullous dermatoses are characterized by the production of autoantibodies to structural proteins of the skin. In most instances, the autoantigens have been identified and are available as recombinant proteins. Utilizing these recombinant forms, specific and sensitive assays have been developed for the detection of circulating autoantibodies in the serum. The detection of autoantibodies in skin or mucous membranes and/or serum is required for the diagnosis of autoimmune bullous dermatoses. The task of the dermatopathologist in the diagnostic process of autoimmune bullous dermatoses is to describe precisely the histopathological findings, to mention differential diagnoses and to recommend how these can be confirmed or excluded by immunopathological and immunoserological studies.