Multiple myeloma (also known simply as myeloma or plasma cell myeloma, or as Kahler's disease after Otto Kahler it's founder) is a hematological malignancy of plasma cells, the cells of the immune system that produce antibodies. Although it initially develops in the bone marrow, it spreads to the peripheral blood, lymph nodes and other organs fairly rapidly.

Symptoms of multiple myeloma are diverse, and very few are specific to the disease. Bone pain is the most common, as the initial stages of the disease focus the growth of malignancy in the bone marrow itself. Some other main symptoms can include:

• malaise - discomfort, uneasiness, or indisposition, often indicative of infection.
• anemia - a reduction in the number of circulating red blood cells.
• infections - as cancer weakens the immune system.
• increased incidence of broken bones - due to breakdown of bone by malignant cells, as well as a tendency to brittle bones.

Often, the diagnosis of multiple myeloma is made incidentally during routine blood tests for other conditions. The antibody that is produced in excess may cause specific medical problems, such as amyloid and chronic renal failure, polyneuropathy and other disorders.