Mucous membrane pemphigoid (MMP) is described as “a group of putative autoimmune chronic inflammatory subepidermal blistering diseases predominantly affecting mucous membranes that is characterized by linear deposition of IgG, IgA or C3 along the basement membrane zone.”1
MMP is the appropriate name for a group of heterogeneous diseases that includes cicatricial pemphigoid (CP), benign MMP, oral pemphigoid, desquamative gingivitis, and ocular CP.1 Until the international consensus meeting in 1999, the terms CP and MMP had been used interchangeably. According to the new diagnostic clinical criteria proposed, MMP is defined as a group of autoimmune blistering diseases characterized by involvement in 1 or more mucosal areas with or without much scarring.1 CP solely involving skin without mucosal involvement is now considered to be a distinct entity from MMP. The subtype of the disease with blistering localized to the scalp and neck, cicatricial alopecia, and no involvement of mucous membranes is known as Brunsting-Perry CP, first described in 1957.2 Thus, CP with only skin involvement and MMP are now considered 2 different clinical phenotypes that may have a similar etiopathogenesis. The patient in this report had mucosal lesions along with skin involvement; hence, she was diagnosed with MMP. Because the terms CP and MMP were used synonymously prior to 2002, both terms are used interchangeably in this discussion.
MMP is a rare, autoimmune, subepidermal blistering disease that affects women 1.5 to 2 times more commonly than men. With no known racial or geographic predilection, the disease has a mean age of onset in the 70s. Mucosal site (ocular, genital, nasopharyngeal, laryngeal, and esophageal) involvement resulting in fibrosis, strictures, blindness, and functional disability is the major cause of morbidity in patients with MMP.
Although several factors have been proposed for the pathogenesis of MMP, a clear mechanism has not been delineated. Autoantibodies to several basement membrane zone components including BP230, BP180, laminin-5, laminin-6, type 7 collagen, integrin β4 subunit, and other unspecified antigens probably play a role in the pathogenesis. Other mechanisms that have been implicated include mediation of cellular immunity, altered cytokine expression, and epitope spreading phenomenon.
The major sequela of MMP is scarring of the involved mucosae and skin; cicatricial alopecia is a rarely reported phenomenon except in cases of the Brunsting-Perry type. In a review of 54 patients with CP, only 4 had cicatricial alopecia.3 Cicatricial alopecia in MMP may be a common but underreported entity or it may be of a clinically insignificant severity in the majority of patients. Alopecia with severe scarring can be a potential but less well-recognized complication, leading to cosmetic disfigurement and psychologic stress for patients.
Treatment of MMP has not been evaluated with well-controlled clinical trials. Managing a patient with MMP requires an interdisciplinary approach involving dermatologists, ophthalmologists, dentists, oral surgeons, primary care physicians, gynecologists, otorhinolaryngologists, and gastroenterologists.1 The treatment modalities reported to be effective in the literature include topical and intralesional corticosteroids, prednisolone, cyclophosphamide, azathioprine, intravenous immunoglobulin, mycophenolate mofetil, cyclosporine, tacrolimus, methotrexate, dapsone, tetracycline, nicotinamide, thalidomide, and plasmapheresis.1 The antitumor necrosis factor-α agents etanercept4 and infliximab5 have also been used in recalcitrant MMP. The choice of therapy is governed by disease severity and its potential complications and by the risk of adverse effects from treatment in these patients. Patients with involvement of only oral mucosa or oral mucosa and skin, so-called low-risk patients, require more conservative treatment than patients with more widespread disease.