BACKGROUND Solitary plasmocytoma is a rare plasmacytic cell tumor, which occurs in the head and neck region and rarely involves the mandible. METHODS We present a unique radiographic presentation of solitary bone plasmocytoma (SBP) occurring in the Jaw. A 63-year-old male presented with the left mandibular swelling and on the conventional radiograph we noticed a lytic lesion with a sunray periosteal reaction. Clinical diagnosis was osteosarcoma but histopathology revealed sheets of plasma cells with cartwheel appearance and expansile bony trabecula suggestive for solitary bone plasmocytoma. 5years after complentary treatment by local radiotherapy he developed malaise, weakness and generalized bone pain and bone marrow aspiration revealed more than 90% plasma cell in the marrow and diagnosis of Multiple Myeloma was confirmed. CONCLUSIONS SBP is radiographically seen as a well-defined radiolucent expansile lytic lesion with cortical thinning and no periosteal reaction. The imaging appearance of periosteal reaction is determined by the intensity, aggressiveness, and duration of the underlying pathology. Osteosarcoma, Metastasis (especially from sigmoid colon and rectum), Ewing s sarcoma, Haemangioma, meningioma and Tuberculosis are the main differential diagnosis of Sunburst periosteal reaction. CONCLUSIONS Sunray periosteal reaction should be included in the differential diagnosis of lytic bone lesion in the mandible.