plasma cell tumor
Meaning of plasma cell tumor: A growth of the antibody factories of the immune system, ranging from a harmless clone to widespread disease in the bones.
Definition of plasma cell tumor
A plasma cell tumor is an abnormal growth of plasma cells, the mature white blood cells that manufacture antibodies. All of the cells descend from a single ancestor, so they pour out identical copies of one antibody that can be measured in blood or urine. The group spans a lone localized deposit, widespread bone marrow involvement, and a symptomless clone found by chance.
What is a plasma cell?
It is the final stage of a B lymphocyte. Once a B cell meets the target its receptor recognizes, it enlarges and converts into a plasma cell, a factory that does nothing but produce antibody against that one target. Most settle in the bone marrow. Because each plasma cell makes only a single kind of antibody, a tumor built from one cell and its descendants floods the blood with one identical protein, known as a monoclonal protein or paraprotein. That protein is what blood tests pick up, and it is the thread linking every member of this group.
What are the types?
| Type | Where the cells sit | Behavior |
|---|---|---|
| Monoclonal gammopathy of undetermined significance | Scattered in the marrow, few in number | Not cancer, with a small yearly chance of progressing |
| Solitary plasmacytoma | One deposit in bone or soft tissue | Local at first, and often progresses later |
| Multiple myeloma | Throughout the bone marrow | Cancer, with bone, kidney and blood effects |
| Plasma cell leukemia | Circulating in the blood | Aggressive and uncommon |
The first entry is the one most often misread. Monoclonal gammopathy of undetermined significance is a precursor state rather than a tumor in the ordinary sense, common in older people and, for most of them, never the cause of trouble. A plasmacytoma is a single mass that can often be treated with radiation alone, while multiple myeloma is present throughout the marrow from the outset.
What damage do they do?
Harm arrives from two directions at once. Cells expanding inside the marrow crowd out normal blood production and switch on the cells that dissolve bone, which brings anemia, bone pain, fractures and calcium released into the blood. Separately, the antibody protein itself does damage: small fragments of it filter into the kidney and block the tubules, and large amounts thicken the blood enough to slow its flow. That split is why treatment addresses the cells and the consequences of the protein as two different problems.
Also known as
Used in a sentence
Protein electrophoresis was ordered once a plasma cell tumor was suspected.
Good to know
Monoclonal gammopathy of undetermined significance is grouped with these tumors but is not cancer, and much of the damage in multiple myeloma comes from the antibody protein the cells release rather than from the bulk of tumor itself.
Word origin
Where “plasma cell tumor” comes from
Plasma comes from the Greek plasma, meaning something molded or formed.