Lymph nodes are small, bean-shaped glands that are part of the body’s immune system. They are commonly identified during medical imaging scans. Discovering subcentimeter lymph nodes on imaging is frequent and typically not a cause for concern. These small nodes are often normal or indicate a benign, temporary process.
What Lymph Nodes Are
Lymph nodes are components of the lymphatic system, a network of organs, vessels, and tissues that maintain fluid balance and protect the body from infection. They function as filters, trapping harmful substances like bacteria, viruses, and abnormal cells as lymph fluid passes through them. Lymph nodes also house specialized immune cells, such as lymphocytes and macrophages, which identify and eliminate foreign invaders. These structures are found in clusters throughout the body, serving as checkpoints for the immune system. When the body encounters an infection or other challenge, these nodes can become more active, leading to changes in their size.
Understanding Subcentimeter Lymph Nodes
“Subcentimeter” lymph nodes are those less than one centimeter (10 millimeters) in their shortest diameter. Nodes of this size are frequently observed on imaging and are generally considered normal or reflective of a reactive process. While small nodes are often reassuring, size alone does not provide a complete diagnosis. Other characteristics, such as shape and internal features, also contribute to the overall assessment.
Common Non-Cancerous Causes of Lymph Node Enlargement
Lymph nodes, even subcentimeter ones, can become more prominent or slightly enlarged due to various non-cancerous conditions. Infections are the most frequent cause, as the nodes swell while fighting off pathogens. Common infections, inflammatory conditions, and reactions to recent vaccinations can lead to temporary lymph node enlargement. This increase in size indicates the lymphatic system is effectively working to clear the issue.
When to Seek Medical Advice
While subcentimeter lymph nodes are often benign, certain signs and accompanying symptoms warrant medical evaluation. A doctor should be consulted if a lymph node exhibits rapid growth, increases in size over several weeks, or persists for more than two to four weeks. Nodes that feel hard, rubbery, or fixed, rather than soft and mobile, are also concerning. Although tender or painful nodes often suggest infection, a painless, persistent enlargement can also be a red flag.
Additional systemic symptoms accompanying swollen nodes should prompt a medical visit. These include unexplained weight loss, night sweats, persistent fever, or fatigue. The location of an enlarged node can also be significant; for instance, a palpable node above the collarbone may be more concerning.
How Lymph Nodes Are Evaluated
When there is concern about lymph nodes, a doctor typically begins with a physical examination. This involves feeling the nodes to assess their size, consistency, tenderness, and mobility. Depending on the findings, further investigation may include blood tests to check for infection or inflammation. Imaging studies, such as ultrasound, CT scans, or MRI, can provide detailed views of the nodes, especially those located deeper in the body.
If these initial evaluations do not provide a clear diagnosis or if a more serious condition is suspected, a lymph node biopsy might be recommended. This procedure involves taking a tissue sample from the node, either through fine needle aspiration or surgical removal. The tissue is then examined under a microscope by a pathologist to determine the exact cause of the enlargement.