구강 점막 유천포창의 상피 기저막에
53 years old female showed repeated ulceration of labial gingival mucosa at upper and lower anterior teeth, which wasa partly desquamated and erythematous lesion. The lesion was slightly extended into vestibule and buccal mucosa in oralcavity, but the similar lesion was not found in other organs by medical inspection. The incisional biopsy including theborder of the ulcerated mucosa and normal mucosa showed a severely inflamed mucosa, of which epithelium was graduallydetached from the underlying conective tissue, so that it was diagnosed as a mucous membrane pemphigoid (MMP)pathologically. The epithelium was thinned, almost lost its rete pegs, and the basement membrane was completely distortedby the epithelial detachement. The inflammatory cell infiltration was mainly composed of small round cells andplasma cells. Immunohistochemistry was performed to know the expression of pathogenetic proteins using antisera ofIgk, E-cadherin, laminin a5, elafin, and eIF5A. The basement membrane at the epithelial detachment was condenselypositive for Igk, and the involved epithelium became atrophic but showed consistently positive reaction of matrix proteinsand protein translation factor, i.e., E-cadherin, laminin a5, elafin, and eIF5A similar to the adjacent normal mucosacontinuous to the MMP lesion. The Igk was also diffusely deposited on the basement membrane of nearby normalmucosa. Many plasma cells infiltrated around the lesion were strongly positive for Igk in their cytoplasms. Therefore, wesuggest that the MMP be characterized by the deposition of Igk on the basement membrane of the detached epitheliumin the absence of no other pathognomic changes of molecular events.