The axillary region, commonly known as the armpit, contains small, bean-shaped lymph nodes that are part of the lymphatic system. This network drains fluid and waste from the breast and surrounding tissues. Due to this direct anatomical connection, the armpit lymph nodes are typically the first location breast cancer cells travel to when spreading outside the primary tumor site. Recognizing changes in these nodes is important for early detection. Any newly identified swelling or lump in this area warrants immediate consultation with a healthcare professional.
The Role of Axillary Lymph Nodes in Breast Cancer Spread
The lymphatic system acts as the body’s drainage network, circulating lymph fluid that contains white blood cells. This fluid collects waste and foreign materials from tissues, filtering them through lymph nodes before returning to the bloodstream. The axillary lymph nodes function as the main drainage basin for the breast tissue, filtering lymph fluid that originates there.
Cancer cells from a breast tumor can enter the lymphatic vessels and become trapped in these nodes, a process known as lymph node involvement or metastasis. Because they are the most proximate filters, axillary nodes are often the first site where breast cancer cells establish a secondary growth outside the breast.
Determining the status of these nodes is a necessary part of breast cancer staging. Finding cancer cells in the lymph nodes indicates the disease has begun to spread and affects treatment decisions. The number of involved nodes also provides information about the prognosis.
Key Physical Signs of Lymph Node Involvement
A potentially cancerous axillary lymph node often presents with distinct characteristics compared to a reactive node caused by infection. A node containing cancer cells is typically firm or hard to the touch, sometimes compared to a small marble or stone. This contrasts with the softer, more rubbery feel of a normal or infection-related node.
A concerning sign is a node that feels fixed or immobile, meaning it does not easily move beneath the skin when pressure is applied. Benign swollen nodes are usually mobile and can be gently rolled under the fingers. Furthermore, cancerous nodes are often painless and non-tender, unlike the soreness associated with nodes reacting to an infection or injury.
While an infection-related node typically shrinks within a few weeks, a node that remains enlarged or continues to grow over several weeks is concerning. Any lump that is deep beneath the skin, increases in size, or does not resolve after a week or two should be professionally evaluated.
Associated Changes in Skin and Sensation
Lymph node involvement can sometimes lead to secondary changes in the skin and sensation of the surrounding armpit area. Localized pain or discomfort may occur, even without a defined lump, though pain is less common with cancerous nodes than infectious ones. This discomfort can sometimes limit arm mobility due to swelling.
The skin itself might show signs such as thickening, redness, or a rash in the immediate area. In rare cases, the skin may develop a dimpled or pitted appearance, known as peau d’orange, which signals a blockage of the lymph vessels. These skin changes may indicate that the lymphatic system is being affected by the spread of cancer cells. Persistent itching, a burning sensation, or increased warmth around the armpit due to inflammation may also occur. Any persistent or unexplained sensory or visible change in the armpit region should be reported to a healthcare provider.
Common Non-Cancerous Causes of Armpit Swelling
The majority of armpit lumps are benign and not related to cancer, often resulting from the immune system responding to a common issue. The most frequent cause of swollen axillary lymph nodes is a local or systemic infection, such as a cold, flu, or cellulitis. In these cases, the nodes swell as they filter out pathogens and are usually painful or tender to the touch.
Temporary axillary lymph node enlargement is a normal immune response to recent vaccinations, including those for influenza or COVID-19, and typically resolves on its own. Allergic reactions to personal care products can also cause localized irritation and subsequent node swelling.
Other non-malignant causes that can present as lumps in the armpit area include:
- Folliculitis, which is an inflammation of the hair follicle.
- Hidradenitis suppurativa, an inflammatory condition of the sweat glands.
- Cysts, which are fluid-filled sacs.
- Lipomas, which are soft, fatty tissue growths.
- Autoimmune disorders, such as lupus or rheumatoid arthritis, which may trigger generalized inflammatory response.
The Importance of Prompt Medical Evaluation
Discovering an armpit lump requires a timely professional evaluation, even though the cause is most often benign. A healthcare provider will begin with a physical examination to assess the lump’s size, texture, mobility, and tenderness, and take a detailed patient history. They will determine if the swelling is associated with a recent illness, injury, or vaccination.
If the node characteristics are suspicious or the lump persists, further diagnostic tools are utilized. The initial imaging test is often an ultrasound of the axilla, which provides a detailed view of the node’s internal structure. Appropriate breast imaging, such as a mammogram, may also be performed depending on the patient’s age and ultrasound findings.
If imaging reveals suspicious features, the definitive step is a biopsy, typically an ultrasound-guided core needle biopsy. This procedure collects a tissue sample for laboratory analysis to confirm or rule out cancer cells. Early diagnosis allows for a broader range of treatment options and leads to the best possible outcomes.