Mucous membrane pemphigoid with generalized blisters: IgA and IgG autoantibodies target both laminin-332 and type XVII collagen.

Mucous membrane pemphigoid (MMP) is a mucous membrane-dominated, subepidermal autoimmune blistering disease in which autoantibodies usually react with the C-terminal domain of type XVII collagen (COL17) or with laminin-332. Only a few cases of MMP with widespread blisters have been reported. Serologically, IgA and IgG class autoantibodies directed against COL17 or IgG autoantibodies directed against laminin-332 in patients with MMP have been well documented. MMP cases in which IgA reacts with laminin-332, however, are extremely rare. We report a case of MMP in a 67-year-old man. Clinical examination revealed extensive mucosal lesions as well as generalized blisters and erosions that healed with scar formation. The disease was intractable to treatment with systemic steroids. Interestingly, in addition to IgG directed against laminin-332 and the noncollagenous 16A (NC16A) and C-terminal domains of COL17, circulating IgA reacting with laminin-332 and with the NC16A domain of COL17 was also detected. This is the first MMP case with circulating IgA and IgG autoantibodies against both laminin-332 and COL17.