Myeloma, also known as plasmacytoma of the bone, is a malignant tumor originating in the hematopoietic tissue of the bone marrow and caused by excessive proliferation of plasma cells. It can present as a solitary lesion or as multiple bone lesions. Abnormal plasma cells infiltrate bones and soft tissues, producing M-proteins, which lead to bone destruction, anemia, kidney dysfunction, and immune abnormalities. The condition is more commonly observed in men over the age of 40 and primarily affects bones that contain hematopoietic marrow, such as the spine, pelvis, ribs, skull, and sternum.
Clinical Features
There is typically an asymptomatic period of varying duration, while in some cases, back pain serves as the initial symptom. Extensive lytic bone destruction can cause pain, pathological fractures, hypercalcemia, anemia, and cachexia. X-ray findings mainly show multiple lytic lesions and widespread osteoporosis. A definitive diagnosis can be made by identifying a large number of abnormal plasma cells through bone marrow biopsy. Serum and urine tests reveal elevated levels of abnormal globulins, with a reversal of the albumin-to-globulin ratio (A/G). Protein electrophoresis abnormalities demonstrate increases in β and γ globulins. A leukemic blood picture may also be observed, and over 40% of patients test positive for Bence-Jones protein in their urine. Additional findings include hypercalcemia and abnormal urine protein electrophoresis.
Treatment
Chemotherapy serves as the primary treatment approach, and appropriate combination drug therapy can extend patient survival. Radiotherapy is effective for localized lesions, especially in cases where surgery is not feasible. For patients with pathological vertebral fractures or cases in which tumors penetrate bone and compress the spinal cord, decompressive surgery is necessary before initiating radiotherapy. Hematopoietic stem cell transplantation may be considered in eligible patients.