This case involves a 16-year-old woman with a posterior cervical tumor. Histologically, it was found to be a extramedullary plasmacytoma (EMP). Immunohistochemically, IgG was present in the plasma cells that were shown to be atypia by the PAP method. Laboratory data revealed no other abnormalities. A surgical excision of the tumor was performed with a dissection of the relevant lymph nodes. Although irradiation and chemotherapy were administered postoperatively, multiple bone metastasis was found a month after the operation, and the patient died 8 months later.