lymphoid
Meaning of lymphoid: The adjective tying together lymphocytes, the organs they live in, and the half of blood production that makes them.
Definition of lymphoid
Lymphoid describes lymphocytes, the white blood cells behind targeted immunity, and the tissue in which they develop and gather. Lymph nodes, the spleen, the thymus, the tonsils and patches in the lining of the gut are all lymphoid. The word also names one of the two branches of blood cell production, the branch yielding lymphocytes rather than red cells or platelets.
How lymphoid is built
- lymph/o Combining form · Latin lymph, lymphatic tissue
- -oid Suffix · Greek resembling, like
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
What counts as lymphoid tissue?
Lymphoid tissue is packed with lymphocytes held in a supporting mesh, and it splits into two groups by job. Primary lymphoid organs are where lymphocytes are made and schooled, and there are two: the bone marrow, where B cells finish training, and the thymus, where T cells do. Secondary lymphoid organs are where trained cells wait and meet whatever the body has caught. These include the lymph nodes, the spleen, the tonsils and adenoids, and sheets of tissue lining the gut and airways.
How is it different from myeloid?
| Lymphoid line | Myeloid line | |
|---|---|---|
| Cells produced | B cells, T cells, natural killer cells | Red cells, platelets, neutrophils, monocytes |
| Main job | Targeted defense that remembers | Oxygen carriage, clotting, immediate defense |
| Where maturing happens | Bone marrow and thymus | Bone marrow |
| Cancers of the line | Lymphomas and lymphocytic leukemias | Myeloid leukemias and marrow failure disorders |
Why does the word turn up in so many reports?
Pathologists name a growth after the cell it came from, so lymphoid appears whenever lymphocytes are involved. A report may describe a lymphoid infiltrate, meaning a crowd of lymphocytes has moved into a tissue, which happens in ordinary infection as much as in disease. It may describe reactive lymphoid hyperplasia, meaning a node has enlarged because it is working hard rather than because it is cancerous. Separating a reactive response from a lymphoid cancer is one of the harder judgments in pathology, and it usually needs surface markers and gene tests rather than appearance alone.
Where does lymphoid tissue sit relative to blood?
Lymphocytes do not stay put. They travel in blood, cross into a lymph node, patrol it, then rejoin the circulation through the lymphatic vessels that drain back into a large vein near the heart. At any moment most lymphocytes are inside lymphoid tissue rather than in the bloodstream, which is why a blood count can look ordinary while a node is visibly swollen, and why lymphoid disease is often found by examining a node rather than by testing blood.
Used in a sentence
The biopsy described a dense lymphoid infiltrate with no evidence of a clonal population.
Good to know
An enlarged lymph node is far more often reactive lymphoid tissue responding to infection than a lymphoid cancer, and the two cannot be separated by size or feel alone.
Word origin
Where “lymphoid” comes from
From the Latin lympha, meaning clear water, the name given to the pale fluid these tissues drain, with the ending -oid, meaning resembling.