Lymph nodes are small, bean-shaped structures that serve as filtering stations for the body’s immune system. They are part of the lymphatic network, which circulates fluid containing white blood cells, filtering out pathogens, cellular waste, and foreign materials. When the body detects an infection or abnormality, the immune cells within the nodes multiply rapidly to fight the threat, causing the nodes themselves to enlarge. Determining if a lump in the armpit is a swollen lymph node is a common concern, and understanding how to identify these structures is the first step toward self-assessment.
Locating and Examining Axillary Lymph Nodes
The armpit, or axilla, contains numerous lymph nodes that drain lymph fluid from the breast, arm, and upper chest wall. To begin the examination, sit or stand with the arm you are checking relaxed and slightly away from the body. This positioning relaxes the muscles and allows for a more thorough palpation of the soft tissue. Use the pads of two or three fingers from your opposite hand to gently press and roll the tissue against the underlying chest wall.
Start by feeling the central area of the armpit, where most of the nodes are concentrated, using a firm but gentle circular motion. Systematically check all five main areas of the axilla, covering the front wall along the pectoral muscle and the back wall along the latissimus dorsi muscle. Next, move to the inner wall along the rib cage, and finish by checking the nodes along the upper arm bone. A normal lymph node is often not palpable, but if felt, it is typically small and soft.
What Swollen Lymph Nodes Feel Like
A healthy, unstimulated lymph node is generally quite small, often measuring less than one centimeter, about the size of a pea. When swelling occurs, the node can enlarge to the size of a kidney bean or larger as immune cells proliferate inside. In this swollen state, a benign or reactive node usually feels soft or slightly rubbery and is freely movable under the skin.
Tenderness or pain when the node is pressed is a key characteristic of inflammation. This tenderness is a reassuring sign, as it often indicates an active, inflammatory process like an infection, known as lymphadenitis. Nodes that are more concerning tend to be hard, almost like a small stone or marble, and are fixed firmly in place. When a node is fixed and non-tender, it raises a higher degree of suspicion for a more serious underlying issue.
Common Reasons for Swelling
The majority of axillary lymph node swelling is due to a common, temporary immune response. Because the nodes in the armpit drain the entire upper extremity and breast area, any localized infection or injury in these regions can cause them to react. For instance, a small skin infection, an ingrown hair, or a scratch on the hand or arm can trigger rapid, localized swelling. This type of reactive swelling is a sign the immune system is working to contain the threat.
Recent vaccinations, particularly those administered into the deltoid muscle such as the COVID-19 or flu shots, are also a frequent and expected cause of temporary swelling. The vaccine stimulates a strong immune reaction in the local drainage nodes, which can lead to noticeable enlargement on the side of the injection. Swelling can also result from systemic illnesses like a common cold, the flu, or mononucleosis, which cause a widespread immune activation. In most of these benign cases, the swelling will subside naturally within a few days to two weeks as the body overcomes the infection or responds to the vaccination.
When to Contact a Healthcare Provider
While most swollen lymph nodes are harmless, certain characteristics necessitate professional medical evaluation. Contact a healthcare provider if the swelling persists without any apparent cause for longer than two to four weeks. Nodes that are rapidly increasing in size or that feel hard, firm, and immovable when palpated are indicators that require immediate attention.
If the swollen node is accompanied by certain generalized symptoms, seek medical consultation. These concerning signs include unexplained and significant weight loss, persistent fevers, or drenching night sweats. These features may indicate a condition requiring specific treatment.