Disease Description Isolated plasmacytoma of bone: A single isolated plasmacytoma originating in the bone is called isolated plasmacytoma of bone (solitary plasmacytoma). Isolated plasmacytoma is a rare malignant plasma cell disease, accounting for approximately 3% of all malignant plasma cell diseases. The age of onset is younger than that of multiple myeloma. Clinical manifestations It is classified as one of the B-cell lymphomas in the WHO 2001 classification of lymphomas. 1. Clinical manifestations are characterized by localized skeletal swelling with pain. The most frequently invaded site is the vertebral skeleton. 2. Other prevalent sites are pelvis, femur, humerus and ribs in order of prevalence, while skull invasion is rare. On X-ray images, the lesions are mostly “porous” or “soap bubble-like” osteolytic lesions, and the boundaries of the lesions are not as sharp and clear as those of multiple myeloma osteolytic lesions. 4. A few patients show sclerosis of the damaged bone. Pathological fractures may occur in the damaged bones. 5. Except for isolated skeletal plasmacytoma, there is no lesion in other bones. 6.The bone marrow picture and blood picture are normal. 7, Only 10-20% of patients with isolated plasmacytoma have increased monoclonal immunoglobulins or light chains in blood and urine. Most patients do not have increased monoclonal immunoglobulins or their polypeptide chain subunits (light chains), nor do they have anemia, hypercalcemia, hyperviscosity syndrome, or renal impairment. Diagnostic criteria The recommended diagnostic criteria proposed by the British Committee for Standardization in Haematology/British Myeloma Society Guidelines Working Group in 2004 are: 1. single region of skeletal destruction due to clonal proliferation of plasma cells; 2. normal bone marrow cytomorphology and bone marrow biopsy outside the local lesion; 3. normal bone marrow examination including long bone x-ray outside the local lesion; 4. absence of plasma cell disease due to Anemia and hypercalcemia or renal failure due to plasmacytosis; 5. Lack of or low levels of serum or urine monoclonal immunoglobulins; 6. No other damage found on MRI scan of vertebrae. Treatment Treatment with local radiation therapy is preferred. If the lesion is limited and easily resectable, local radiotherapy is more effective after surgical resection. When compression fractures occur in vertebral damage, especially when the complication of neurological damage may lead to paraplegia, it is feasible to resect the diseased vertebrae, artificial vertebral body replacement, followed by local radiotherapy, which can achieve satisfactory results.