Lymph nodes are small, bean-shaped structures that form a part of the body’s extensive immune system. These organs are located throughout the body, serving as critical checkpoints within the lymphatic network. They connect via lymphatic vessels, which transport a fluid called lymph. This fluid carries waste products, nutrients, and immune cells throughout the body.
Location in the Upper Arm
Lymph nodes are present in the upper arm, primarily concentrated in the axilla, or armpit, which contains a significant cluster of lymph nodes (20-49). These axillary lymph nodes are positioned to drain lymph fluid from the entire upper limb, chest wall, and breast. While axillary nodes are the most prominent, smaller lymph nodes, such as cubital nodes, can also be found along the upper arm near the elbow. These smaller nodes typically drain specific areas of the forearm and hand before directing lymph towards the larger axillary groups, and are often not noticeable unless they become enlarged or swollen.
Their Role in the Body
Lymph nodes function as filters for the lymphatic fluid, playing a central role in the body’s defense. As lymph fluid passes through them, these nodes trap harmful substances such as bacteria, viruses, and abnormal cells. They are home to various immune cells, including lymphocytes and macrophages, which identify and eliminate foreign invaders. This filtering and immune cell activation are essential for an effective immune response against infections and diseases. Lymph nodes are central to the immune system, acting as centers where immune cells are activated to combat threats and protect the body from pathogens and cellular abnormalities.
Common Causes of Swelling
Swollen lymph nodes indicate they are actively fighting an infection or other health issue. The most frequent cause of swollen lymph nodes in the armpit is an infection, as these nodes drain the arm and surrounding areas. Common viral infections (e.g., flu, mononucleosis, HIV) and bacterial infections (e.g., cellulitis, cat scratch disease) are common causes of enlargement. Physical injuries to the arm or hand can also cause temporary swelling as the body responds to trauma. Less commonly, inflammatory conditions or autoimmune diseases (e.g., lupus, rheumatoid arthritis) might cause enlargement, and while less common, swollen lymph nodes can signal more serious conditions, including certain cancers (e.g., lymphoma, leukemia, or spread of breast cancer).
When to Seek Medical Advice
While often a sign of routine infection, certain characteristics of swollen lymph nodes warrant medical evaluation. Consult a healthcare professional if a swollen lymph node in your upper arm or armpit persists for over two to four weeks, or continues to grow. Nodes that feel hard, are fixed, or are not tender should also be examined. Additional concerning symptoms include unexplained weight loss, night sweats, persistent fever, or unusual fatigue. If swelling occurs in multiple areas (e.g., armpit and groin), or if the node causes significant pain or discomfort, seek medical advice, as only a medical professional can accurately diagnose the cause and recommend appropriate steps.