Multiple myeloma is characterized by the neoplastic proliferation of a single clone of plasma cells, which proliferates in the bone marrow and may result in extensive skeletal destruction with osteolytic lesions and fractures. In more than two-thirds of patients, bone pain, particularly in the back, chest, and extremities, is present at the time of diagnosis. The pain is aggravated by movement and change of position. Because of vertebral collapse, the patient's height may be reduced by several inches. Weakness and fatigue, secondary to anemia, are also common complaints. The most common physical finding is pallor. The liver is palpable in approximately 20% of patients with multiple myeloma. Treatment is usually chemotherapy with symptomatic treatment of pain (analgesics). Radiation therapy is used for patients with disabling pain or those who do not respond to chemotherapy.