A rare case of extramedullary plasmacytoma in the sino-nasal cavity is presented. During a prolonged clinical course, the tumor has recurred several times after irradiation, chemotherapy and surgery, and presented in the clavicular bone as well. Immunohistochemical staining of each tumor showed IgA kappa phenotype, and immunoelectrophoresis of the serum showed overproduction of IgA with kappa light chains. Although an elevation of serum IgA persists, the patient has remained well without evidence of overt multiple myeloma.