Immunohistopathological analyses of a case of pemphigus vegetans with antibodies against desmoglein 1 and desmocollins 1–3

Abstract Pemphigus vegetans is a rare type of pemphigus characterized by vegetative lesions primarily localized to the intertriginous area. Despite its unique clinical presentation, the underlying pathomechanism remains unclear owing to the rarity of the disease. We report a case of pemphigus vegetans with antibodies against desmoglein 1 and desmocollins 1–3. Furthermore, immunohistochemical analyses were performed to address the pathogenesis of this disease. A 73‐year‐old man presented with multiple vegetative plaques with erythema on the trunk, groins, and extremities. Mucosal lesions were not observed. Laboratory examinations revealed mild leukocytosis with eosinophilia. A histopathological examination of the skin lesion showed epidermal hyperplasia and intraepidermal abscesses with marked infiltration of neutrophils and eosinophils, and infiltration of lymphocytes and eosinophils into the upper derms. Bacterial culture of the skin tissue was positive for Staphylococcus aureus . Direct immunofluorescence showed deposits of IgG and C3 on keratinocyte surfaces in the epidermis. Autoantibodies against desmoglein 1 and autoantibodies against desmocollin 1, desmocollin 2, and desmocollin 3 were detected by enzyme‐linked immunosorbent assays. The diagnosis of pemphigus vegetans was made. Initiation of prednisolone (1.0 mg/kg/day) gradually improved his skin symptoms. We performed immunohistochemical analyses of the lesional skin, which revealed infiltration of CD3‐positive, CD4‐positive, and CD68‐positive cells in the upper dermis, but CD20‐ or CD56‐positive cells were negative. In addition, the present case showed more prominent infiltration of IL‐17A‐ and IL‐22‐positive cells in the upper dermis than in pemphigus foliaceus, a type of pemphigus with autoantibodies against desmoglein 1. Furthermore, these cells co‐expressed CD3 and CD68. We hypothesized that IL‐22 and IL‐17A produced by T cells and macrophages and their dysregulation might be involved in the pathogenesis of pemphigus vegetans. Additionally, skin colonization and/or infection with Staphylococcus aureus could potentially contribute to the pathogenesis of the disease.