The solitary plasmacytoma is a monoclonal unifocal neoplastic proliferation of plasma cells with histopathologic characteristics similar to those of multiple myeloma. Its etiology is unknown, and rarely the jaws. VMS patient, 56 years old, female, melanoderma in treatment of breast cancer, referred to oncologist for the preparation of the oral cavity in order to start the radiotherapy treatment. On physical examination, presence was seen as a fluctuation in the region of mandible body, with granulation tissue and purulent drainage without dental involvement. In-radiographic examination showed the presence of intraosseous lesion long, radiopaque, surrounded by radiolucent halo. The chance of diagnosis was chronic osteomyelitis diffuse, cement-osseous dysplasia, complex odontoma, osteoma and ossifying fibroma. After biopsy, was found to be a plasmacytoma. The objective of this work is to present a clinical case report of solitary bone plasmacytoma with primary involvement of the oral cavity, emphasizing their clinical, radiographic and histological features.