hematology

Plasma cell dyscrasias

Multiple Myeloma
By
Dr. Muna A. Kashmool

Definition

• Multiple myeloma is a neoplastic plasma cell dyscrasia (PCD) that generally produced a monoclonal immunoglobulin protein, characterized by a clinical pentad: (a) anemia; (b) a monoclonal protein in the serum or urine, or both, (c) abnormal bone radiographs and bone pain; (d)hypercalcemia; and (e) renal insufficiency or failure. With the exception of monoclonal gammopathy of undetermined significance (MGUS), it is the most common PCD.

Epidemiology of Myeloma

• Approximately 14,400 new cases of multiple myeloma are diagnosed each year. The median age at diagnosis of myeloma is 71 years of age. Mortality rates are consistently higher among men than women and among blacks than whites in each age group.

Etiologic Factors

1) Radiation Exposures
Atomic Bomb Exposure.

2) WORKPLACE EXPOSURES

Agricultural Occupations and Exposures. Several epidemiological studies have evaluated the risk of myeloma among agricultural workers.


Metal Industries. Workers in various metal occupations and industries have been reported to have an increased myeloma risk.
Diagnostic and Therapeutic X-rays.

4) PRECURSOR MEDICAL CONDITIONS

Monoclonal Gammopathy of Undetermined Significance. MGUS is considered a potential precursor condition for multiple myeloma.

PATHOGENESIS AND PATHOPHYSIOLOGY

• Normally, plasma cells make up a very small portion (less than 1%) of cells in the bone marrow. Myeloma plasma cells, however, have specific adhesion molecules on their surface allowing them to target bone marrow. After they enter the bone marrow, these adhesion molecules allow them to attach to structural cells called stromal cells. Once myeloma cells attach to bone marrow stromal cells, several interactions cause myeloma cells to grow (see figure):

Clinical Manifestations

• The symptoms of multiple myeloma may be nonspecific and include fatigue, bone pain, easy bruising and bleeding, recurrent infections, manifestations of anemia, hypercalcemia, lytic bone lesions, hyperviscosity, thrombocytopenia, and hypogammaglobulinemia. Weakness, infection, bleeding, and weight loss. Hypercalcemia, spontaneous bone pain. Tumor fever is present in less than 1% of presenting patients.

• Monoclonal Proteins

• The protein (also known as M component, myeloma protein, or spike) is a hallmark of the disease; 97% of myeloma patients have an intact Ig or a free light chain that can be detected by protein electrophoresis,

• Criteria For Diagnosis Of Plasma Cell Myeloma

• Major criteria
• Plasmacytomas on tissue biopsy
• Marrow plasmacytosis with>30% plasma cells
• Monoclonal globulin spike on serum electrophoresis
• Minor criteria
• Marrow plasmacytosis 10-30%
• Monoclonal globulin spike present, but less than the levels defined above l.
• Lytic bone lesions