A 73-year-old woman was treated 8 years previously for synchronous breast and uterine neoplasms. She presented with a severe sore throat, odynophagia, dysphonia, dyspnoea, ocular irritation and weight loss over the last 3 months. Physical examination revealed ulcerations in the oral cavity, posterior pharyngeal wall and supraglottic larynx, nasal crusting, bilateral conjunctivitis and three cutaneous blisters. A diagnosis of anti-laminin 5 mucous membrane pemphigoid was retained, based on skin biopsy, direct immunofluorescence and immunoprecipitation. A positron emission tomography (PET)-CT detected multiple adenopathies. Cytology revealed adenocarcinoma with an immunocytology compatible with a breast origin and this was considered as a late metastatic recurrence of her previous breast cancer. A treatment of prednisone, dapsone and hormonotherapy was introduced, but intravenous immunoglobulin and rituximab were added due to new mucosal lesions. Despite treatment, a posterior laryngeal scar and bilateral symblepharon were developed. After 3 years, the patient is still alive and reports a satisfactory quality of life.