Bullous pemphigoid associated with internal malignancies: identification of 180‐kDa antigen by Western immunoblotting

We report three cases of bullous pemphigoid associated with internal malignancies. Two cases were associated with gastric cancer and one with rectal cancer. Immunoblot analysis, using epidermal extract of normal human skin, revealed that these patients' sera reacted only with bullous pemphigoid antigen with a molecular weight of 180 kDa (BP180). The relationship of BP180 to malignant tumours is discussed.