Introduction: Linear IgA dermatosis (LAD) is a rare subepidermal autoimmune bullous disease (AIBD) defined by predominant or exclusive immune deposits of immunoglobulin A at the basement membrane zone of skin or mucous membranes. This disorder is a rare, clinically and immunologically heterogeneous disease occurring both in children and in adults. The aim of this project is to present the main clinical features of LAD, to propose a diagnostic algorithm and provide management guidelines based primarily on experts' opinion because of the lack of large methodologically sound clinical studies.Methods: These guidelines were initiated by the European Academy of Dermatology and Venereology (EADV) Task Force Autoimmune Bullous Diseases (AIBD). To achieve a broad consensus for these S2k consensus‐based guidelines, a total of 29 experts from different countries, both European and non‐European, including dermatologists, paediatric dermatologists and paediatricians were invited. All members of the guidelines committee agreed to develop consensus‐based (S2k) guidelines. Prior to a first virtual consensus meeting, each of the invited authors elaborated a section of the present guidelines focusing on a selected topic, based on the relevant literature. All drafts were circulated among members of the writing group, and recommendations were discussed and voted during two hybrid consensus meetings.Results: The guidelines summarizes evidence‐based and expert opinion‐based recommendations (S2 level) on the diagnosis and treatment of LAD.Conclusion: These guidelines will support dermatologists to improve their knowledge on the diagnosis and management of LAD.

Pemphigus is a group of blistering disorders characterized by the formation of intraepithelial blisters in skin and mucous membranes induced by the binding of circulating autoantibodies to intercellular adhesion molecules. The pathogenesis is complex and not fully understood; however, genetic predisposition and various triggers are widely accepted as key factors in pemphigus development. A few cases of new‐onset pemphigus following coronavirus disease 2019 (COVID‐19) vaccination have already been published. The present paper reports a total of two cases of pemphigus foliaceous and three cases of pemphigus vulgaris that occurred following vaccinations against COVID‐19, with anamnestic, clinical, and diagnostic data collection suggesting assumptions over a possible causal correlation.

Multicentric reticulohistiocytosis (MRH) is the most frequently described form of reticulohistiocytosis (RH), and it is classified as a class IIb non-Langerhans cell histiocytosis. It has been designated as multicentric, being characterized by multisystemic involvement. In fact, although mainly involving the skin, along with the joints, it is a systemic inflammatory condition potentially involving every internal organ. As MRH-related skin findings can mimic rheumatoid nodules or Gottron papules, the histopathology of the cutaneous lesions is often necessary for the correct diagnosis. Approximately one-third of MRH patients have confirmed concomitant autoimmune disorders. A wide variety of autoimmune disorders associated with the disease have been reported in the literature, suggesting immune dysfunction as a factor in the pathophysiology of MRH. A case of MRH associated with autoimmune manifestation is reported in the context of a mini review of the literature, with a focus on clinical presentation, treatments, and treatment outcomes. Moreover, eight cases of MRH associated with autoimmune diseases are briefly discussed.

Bullous pemphigoid (BP) and pemphigus vulgaris (PV) represent the most prevalent conditions among autoimmune bullous skin diseases, considered a major cause of severe morbidity and, in certain cases, mortality. The hallmark of the two diseases is the presence of autoantibodies directed against proteins located in the basement membrane of the skin, which determines the formation of blisters. In recent years, interest in the role of microbiota in relation to health-disease status has progressively increased. In particular, based on the gut–skin axis, accumulating evidence has emerged on the potential association between the composition and diversity of microbial communities in the gut, skin, and even in the oral cavity and the risk of developing BP and PV. Dysbiosis, characterized by a generally higher relative abundance of Firmicutes and a depletion of probiotics/beneficial species, might contribute to the pathogenesis of both diseases. Despite the still limited number of studies and the need for further large-scale multicenter studies, the knowledge gathered so far is suggestive of a novel modifiable risk factor representing a potential target for adjuvant treatments of these disabling and life-threatening conditions.