A 46-year-old male patient referred to Department of Oral Medicine, with the primary chief complaint of a painless swelling in the right side of mandibular. A panoramic radiograph revealed a well-defined, multilocular radiolucent bony lesion with thin and straight septa in the right side of mandible extending from distal of canine to mesial of third molar. Histological examination showed a solid proliferation of atypical plasmacytoid cells, which was indicative of plasmacytoma. A systemic workup for the final diagnosis was performed to rule out multiple myeloma.