Peristomal and generalized bullous pemphigoid in patients with underlying inflammatory bowel disease: is plectin the missing link?

Bullous pemphigoid (BP) is a blistering disorder of the skin and mucosa that may coexist with inflammatory bowel disease (IBD). The authors' experiences with peristomal and generalized BP in five patients (three with ulcerative colitis [UC] post colostomy surgery and two with Crohn's disease [CD] post ileostomy surgery, time since surgery 5 to 20 years) is described. The patients presented with peristomal blisters and erosions, subsequently confirmed as BP by skin biopsy. Treatments for the skin disease included potent alcohol-based topical corticosteroids, oral tetracyclines, and oral corticosteroids. In three patients (two with UC, one with CD), the initially localized peristomal disease later became generalized across the skin; these patients were more likely to require systemic immunosuppressive therapy. Because an involvement of plectin, a cytoskeletal protein that attaches skin and mucosal cells to their extracellular matrix, in IBD has been shown, it is possible that this protein forms the missing link between IBD and BP via epitope spreading. The inflammation of IBD exposes plectin, stimulating a secondary immune response that may, in susceptible individuals, crossreact with the skin, provoking BP. Further research into this area could enable clinical testing for plectin auto-antibodies in patient sera, possibly preempting the development of BP and expediting the initiation of early effective treatment.