Multiple Myeloma
Also called malignant plasmacytoma, plasma cell myeloma, and myelomatosis, multiple myeloma is a disseminated neoplasm of marrow plasma cells. The disease infiltrates bone to produce osteolytic lesions throughout the skeleton (flat bones, vertebrae, skull, pelvis, and ribs). In late stages, it infiltrates body organs as well (liver, spleen, lymph nodes, lungs, adrenal glands, kidneys, skin, and GI tract).
Multiple myeloma strikes mostly males older than age 40. It usually carries a poor prognosis because by the time it’s diagnosed, it has already infiltrated the vertebrae, pelvis, skull, ribs, clavicles, and sternum. By then, skeletal destruction is widespread and, without treatment, leads to vertebral collapse. Within 3 months of diagnosis, 52% of patients die; within 2 years, 90% die. If the disease is diagnosed early, treatment can commonly prolong life for 3 to 5 years.
Causes
Although the cause of multiple myeloma isn’t known, genetic factors and occupational exposure to radiation have been linked to the disease.
Complications
Multiple myeloma can cause infections (such as pneumonia), pyelonephritis (caused by tubular damage from large amounts of Bence Jones protein, hypercalcemia, and hyperuricemia), renal calculi, renal failure, hematologic imbalance, fractures, hypercalcemia, hyperuricemia, and dehydration.
Patients may also develop a predisposition toward bleeding because of impaired
platelet function and thrombocytopenia. This bleeding usually occurs in the GI tract or the nose.
platelet function and thrombocytopenia. This bleeding usually occurs in the GI tract or the nose.
Understanding Bence Jones protein
The hallmark of multiple myeloma, this protein—a light chain of gamma globulin—was named for Henry Bence Jones, an English physician. In 1848, he noticed that patients with a certain bone disease excreted a unique protein—unique in that it coagulated at 113° to 131° F (45° to 55°C) and then redissolved when heated to boiling.
It remained for Otto Kahler, an Austrian, to demonstrate in 1889 that Bence Jones protein was related to myeloma. Bence Jones protein isn’t found in the urine of all multiple myeloma patients, but it’s almost never found in patients without the disease.
Assessment
The patient may have a history of pathologic fractures. He usually complains of severe, constant back pain, which may increase with exercise. The patient may also report symptoms similar to those of arthritis, such as aches, joint swelling, and tenderness, probably from vertebral compression. Other complaints may include numbness, prickling, and tingling of the extremities (peripheral paresthesia).
Inspection may reveal that the patient has pain on movement or weight bearing, especially in the thoracic and lumbar vertebrae.
As the disease advances, the patient will become progressively weaker because of vertebral compression, anemia, and weight loss. As the nerves associated with respiratory function are affected, he may develop pneumonia as well as noticeable thoracic deformities and a reduction in body height of 5″ (12.7 cm) or more as vertebral collapse occurs.
Diagnostic tests
Complete blood count shows moderate or severe anemia. The differential may show 40% to 50% lymphocytes but seldom more than 3% plasma cells. Rouleau formation, commonly the first clue, is seen on differential smear and results from elevation of the erythrocyte sedimentation rate.
