Lymph nodes are small, bean-shaped structures that function as filters within the body’s lymphatic system. This network is a crucial part of the immune system, transporting a fluid called lymph, which contains infection-fighting white blood cells, throughout the body. The nodes trap and neutralize foreign substances, damaged cells, and impurities, including cancer cells. The armpit, or axilla, contains a large cluster of these nodes, draining lymph fluid from the arm, chest wall, and breast. When these nodes are actively filtering a threat, they often swell, signaling a problem that can range from a common infection to a more serious condition like cancer.
Primary Localized Symptoms in the Armpit
The most frequent sign of a potential issue in the axilla is a palpable mass or swelling, known medically as lymphadenopathy. This enlargement occurs due to the accumulation of abnormal cells or an immune response. The swelling may be felt deep within the armpit cavity or near the breast or chest wall, as the axillary nodes drain these areas. Unlike swelling caused by an infection, which is typically painful and tender to the touch, cancerous enlargement of the lymph nodes often begins as a painless lump.
Some individuals may experience a dull ache or localized discomfort as the swollen node presses against nerves or surrounding structures. The skin over the affected area might also show subtle changes, though this is less common than the swelling itself. Certain types of lymphoma that affect the skin, known as cutaneous lymphomas, can cause localized rashes, thickening, or small, raised bumps in the armpit region.
Secondary Systemic Symptoms
Beyond localized changes in the armpit, certain lymph node cancers, particularly lymphomas, can cause non-specific, body-wide reactions known as B symptoms. These systemic symptoms are important for diagnosis and staging. One such symptom is an unexplained, persistent fever, often defined as a temperature of 100.4°F (38°C) or higher that comes and goes without a clear infectious cause.
Another common B symptom is drenching night sweats, which are severe enough to soak through clothing and bedding. Unexplained weight loss is also considered a B symptom, typically defined as losing more than 10% of one’s body weight over a six-month period without dieting or increased physical activity. Many people with lymph node cancer also report generalized fatigue, which is an extreme tiredness that does not improve even with rest.
Characteristics of Concerning Swelling
While many armpit lumps are benign reactions to infections, specific physical characteristics of the swelling can suggest a higher possibility of malignancy. A cancerous lymph node often feels distinctly hard or rubbery to the touch, a texture sometimes compared to pressing on a chin or a piece of rubber. In contrast, nodes swollen from infection tend to be softer and more yielding.
A key differentiating feature is the lump’s mobility; benign, reactive lymph nodes are usually mobile and can be easily moved under the skin when pressed. Malignant lymph nodes, however, frequently become fixed or matted together, anchored firmly to the surrounding tissue. Cancerous nodes are also more likely to be painless, while tender or painful lumps are more common with an inflammatory or infectious process. Furthermore, a malignant node tends to either continuously grow or persist in size, often exceeding a diameter of 1.5 centimeters, rather than shrinking after a few weeks as an infectious swelling would.
When to Seek Medical Attention
Any newly discovered or unexplained lump in the armpit should prompt a medical evaluation, regardless of how it feels. It is especially important to consult a healthcare professional if a lump persists for more than two to four weeks, even if it is not painful. Swelling that continues to increase in size or shows no sign of resolving after a suspected infection has been treated should also be investigated promptly.
Actionable advice includes seeking help immediately if the armpit swelling is accompanied by any of the systemic B symptoms, such as recurring fevers, drenching night sweats, or significant, unexplained weight loss. Early detection is paramount. Only a medical professional can determine the cause of the swelling through examination and diagnostic tests, such as imaging or a biopsy. Present these specific concerns to a doctor for an accurate assessment.