Successful treatment of mucous membrane pemphigoid with the anti-CD-20 antibody rituximab.

101 Letters to the Editor Sir, Mucous membrane pemphigoid (MMP) is an often difficult to treat autoimmune bullous disease characterized by circulating auto-antibodies targeting the dermo-epidermal junctional zone (1–3). Due to limited disease control and/or severe adverse reactions to glucocorticoids and conventional immunosuppressants, alternative treatment options are frequently needed. We describe here the first successful therapy of refractory MMP with rituximab, a humanized anti-CD20 monoclonal antibody depleting B-lymphocytes (4, 5), that resulted in a complete and persisting remission. A 69-year-old man presented with a 16-month history of conjunctivitis. Six weeks prior to admission he developed blisters on the upper and lower extremities and the shoulders. On physical examination, he presented with reddened conjunctivae and multiple blisters on erythematous skin on the extremities and trunk. Additionally, erosive lesions were seen at the perianal mucosa, while genital and oral mucous membranes were not affected. Histopathological examination of lesional biopsies of the skin and oral mucosa revealed a subepidermal split. Peri-lesional direct immunofluorescence microscopy showed linear deposits of IgG and C3 at the dermo-epidermal junction (Fig. 1a). Indirect immuno-fluorescence of sodium chloride-split skin revealed circulating IgG auto-antibodies labelling the roof of the artificial blister (titre 1: 80; Fig. 1b). While antibodies against BP180 NC16A could not be detected by enzyme-linked immunoassay (ELISA), Western blot employing keratinocyte supernatant allowed detection of IgG antibodies directed against LAD-1, the extracellular portion of BP180. Furthermore, immunoblotting using recombinant BP180 4575, which represents the C-terminal part of BP180, confirmed the presence of circulating IgG antibodies against that protein (Fig. 1c). Based on these findings, the diagnosis of MMP was made and a therapy with methylprednisolone (0.5 mg kg –1 body weight) and dapsone (100 mg daily) was initiated. Unfortunately , the transaminases increased within the next 3 weeks, which was attributed to dapsone-induced hepatotoxicity; dapsone was therefore discontinued. Since the conjunctivae did not improve and new blisters continued to arise at the integument we began intravenous pulse therapy with dexamethasone (100 mg daily on 3 consecutive days) and cyclophosphamide (500 mg once per course), which was repeated at weeks 2, 5 and 9. Oral methyl-prednisolone (20 mg daily) was applied between the dexametha-sone/cyclophosphamide pulses. With this treatment, the skin and conjunctival lesions slightly improved. However, due to elevating liver enzymes cyclophosphamide application had to be stopped, while 4-weekly dexamethasone pulses were continued. Since the patient's insulin-dependent diabetes mellitus worsened, while the increased liver enzymes only partially resolved, there …