Definition:
Multiple myeloma (MM) is a malignant bone marrow–based, plasma cell neoplasm associated with abnormal protein production.
Multiple Myeloma may also called myelomatosis.

Epidemiology:
Multiple myeloma accounts for about 2 % of all types of malignant diseases, about 10 % of hematological diseases, and about 15 % of lymphoid malignancies.
Multiple myeloma is slightly more common in males than in females, and it is twice common in black than white people.
98% of cases occur over the age of 40 years with a peak incidence in the 7th decade.

Etiology:
Exact cause is unknown; but radiation, viral infections, toxins, chemicals, and chromosomal abnormalities may be the cause/s.
Chromosomal abnormalities ( 18 % - 35 % of MM patients ); these patients have a worse prognosis, a higher rate of disease acceleration, and decreased survival.

Clinical Signs & Symptoms:
Fatigue, excessive thirst and urination, nausea, bone pain, bone fractures, unexpected infections, weakness and numbness in the legs, renal insufficiency (Myeloma kidney), hypercalcemia, amyloidosis (in 5% of cases), weight loss & night sweats (in advanced cases), abnormal bleeding tendency, thrombocytopenia.
CRAB is a term used to describe the main symptoms of multiple myeloma (C= refers to Calcium problems, R= renal problems, A= anemia, B= bone problems)

Laboratory Findings:
Anemia, granulocytopenia, thrombocytopenia.
ESR (Erythrocyte Sedimentation Rate) > 100 mm/hour.
Blood film shows rouleaux with a bluish background staining.
Bone marrow shows >10% plasma cells.
Increase in serum total protein, LDH (Lactate Dehydrogenase), and uric acid levels.
Hypercalcemia.
Protein electrophoresis shows monoclonal spike in the gamma region.
Bence-Jones protein (immunoglobulin light chain) in urine (in some cases of multiple myeloma).
Serum β2 microglobulin (β2M) often raised and higher levels correlate with worse prognosis.

Radiology:
X-rays, CT scan, MRI or PET.

Prognostic Tests:
Hemoglobin.
β2 microglobulin.
Creatinine.
Albumin.
Tests to show the extent of skeletal disease.

Treatment:
Chemotherapy.
Supportive.
Radiation.
Transplantation (bone marrow or stem cell).

Prognosis:
The prognosis of MM is poor.
Median survival of only 6 months without therapy.
The median survival can be increased to 3 years with chemotherapy.
Increased survival has been reported with autologous bone marrow & peripheral blood stem cell transplants.
Infection is a major cause of death.