Immunobullous disease and ulcerative colitis: a case series of six patients.

Cases of immunobullous skin disease associated with ulcerative colitis (UC) have been previously reported in the literature. There is no clear explanation for this association. In this series, we report six cases of immunobullous disease in patients with UC and discuss potential mechanisms of pathogenesis proposed to explain these concomitant diseases. The clinical presentation, immunopathology and treatment of six new cases are described and analysed. We report six patients, two with linear IgA bullous dermatosis (LABD), one with bullous pemphigoid (BP), one with mucous membrane pemphigoid (MMP) and two with IgA pemphigus. The patients' ages ranged from 33 to 66 years at the onset of their skin disease, and all but one case had a documented age of UC onset, confirmed with colonoscopy, prior to the development of skin disease. Direct immunofluorescence results in these patients demonstrated IgA basement membrane zone (BMZ) antibodies in the LABD cases, IgG antibodies at the BMZ in the BP and MMP cases, and IgA cell surface antibodies in the patients with IgA pemphigus. Additionally, indirect immunofluorescence was positive in one of the patients with LABD, the patient with BP and both of the patients with IgA pemphigus. The temporal association of UC and skin disease, in addition to the resolution of skin disease with total colectomy in one case, suggests colonic mucosal antigenic stimulation driving immune activation and leading to immunobullous skin disease.