Matted lymph nodes are groups of lymph nodes that have become stuck together, forming a single mass. Lymph nodes are small, bean-shaped structures that are part of the immune system. They help the body fight infections by filtering out harmful substances. Normally, lymph nodes are separate from one another, but in certain conditions, they can clump together and feel like one solid lump.
The term “matted” refers to lymph nodes that are no longer individual and mobile but instead merge into a dense mass. This change gives them a firm or fixed texture, which distinguishes them from healthy lymph nodes, which are soft and move easily under the skin.
Lymph nodes can become matted for several reasons:
In these cases, scar tissue, inflammatory cells, or invading cancer cells cause the lymph nodes to merge, forming a solid, immobile mass.
Pathologists usually cannot determine the exact number of lymph nodes within a matted group. Once the lymph nodes are fused, they cannot be separated during examination, even under the microscope. However, pathologists may estimate the number of lymph nodes based on the structure of the mass and describe the size of the aggregate. This helps convey important information about the extent of the disease.
Matted lymph nodes are important because they can indicate serious underlying conditions. In cases of metastatic cancer (when cancer spreads to the lymph nodes), matted lymph nodes show that more than one lymph node is involved and that the cancer has grown outside the boundaries of the lymph nodes into surrounding tissues (a process called extranodal extension). This suggests that the disease is more advanced, which may affect treatment decisions and the overall prognosis.
Matted lymph nodes are also seen in infections like tuberculosis or inflammatory conditions like sarcoidosis, indicating that the immune system has been responding aggressively to a chronic problem.
Pathologists determine that lymph nodes are matted by examining a tissue sample under the microscope. They look for signs that the nodes have fused, including:
Imaging studies like CT or MRI scans may also show matted lymph nodes as a solid mass. However, the final diagnosis and description come from directly examining the tissue under the microscope.