Finding a lump in the armpit, or axilla, can be worrying due to the region’s close association with lymph nodes and breast tissue. The axilla contains numerous lymph nodes that filter the immune system, making this area a common site for swelling during infection or illness. While a lump may signal a serious condition, most are benign and related to common causes. Any persistent or unusual mass in this area should be evaluated by a healthcare professional immediately.
Defining the Physical Characteristics of Concern
A potentially cancerous lump often exhibits specific physical characteristics that differentiate it from a typical swollen lymph node caused by infection. A malignant mass is frequently described as feeling notably hard, dense, or firm, sometimes compared to the texture of a small stone or marble beneath the skin. This hardness results from the rapid, disorganized growth of cancerous cells.
The mobility of the lump is another important indicator, as cancerous masses tend to be fixed. This occurs because the tumor has likely invaded or adhered to the surrounding tissue structures, preventing it from being easily pushed around under the skin. In contrast, benign lumps are often soft, rubbery, and easily movable.
A cancerous lump may also have irregular or poorly defined borders, unlike the smooth, oval shape of a normal lymph node. If the lump persists over several weeks, gets progressively larger, or produces secondary lumps nearby, it raises suspicion. Although a lump may not be visually apparent, a large mass can sometimes cause a subtle bulging or noticeable change in the contour of the armpit skin.
Common Benign Causes of Armpit Swelling
The majority of armpit lumps are not malignant and stem from a variety of non-cancerous origins. The most frequent cause involves the enlargement of the axillary lymph nodes as they respond to a localized or systemic infection. Conditions like a common cold, flu, or a minor infection in the arm, hand, or breast can cause these nodes to swell temporarily as they filter pathogens.
Recent vaccinations, such as those for COVID-19 or influenza, can also trigger a localized immune response, resulting in swollen lymph nodes closest to the injection site. These reactive lymph nodes are generally painful, soft, and movable. Non-lymph node causes of lumps include cysts, which are fluid-filled sacs beneath the skin, and lipomas, which are harmless, soft growths of fatty tissue.
Skin-related issues are another common source of benign lumps, particularly in an area subject to shaving and friction. Folliculitis, an inflammation of the hair follicles often caused by shaving, and hidradenitis suppurativa, a chronic condition involving blocked and inflamed hair follicles, can both create painful, boil-like lumps. These lumps often resolve on their own once the underlying infection or irritation clears.
Associated Symptoms Beyond the Lump
When evaluating an armpit lump, a medical professional considers the physical characteristics of the mass and any accompanying systemic or localized symptoms. Certain generalized symptoms, collectively known as B-symptoms, are particularly concerning when they occur alongside a persistent lump. These include unexplained, persistent fevers, drenching night sweats, and significant, unintentional weight loss.
The presence of these systemic signs suggests the possibility of a body-wide process, such as lymphoma or an inflammatory disease, rather than a simple localized infection. Localized symptoms in the skin surrounding the lump can also be noteworthy. This may involve persistent skin changes such as redness, irritation, or thickening that does not resolve with typical skin care.
If the lump is related to breast cancer, the skin over the breast or near the lump may show signs like dimpling, often described as an orange-peel texture, or nipple discharge. While a cancerous lump may sometimes be painless, the combination of a firm, fixed mass with any of the B-symptoms significantly increases medical concern.
Immediate Next Steps and Medical Consultation
Upon discovering an armpit lump, the most important step is to schedule an appointment with a healthcare provider without delay. This is especially true if the mass is hard, fixed, or has persisted for more than two weeks. Waiting for the lump to resolve without medical input is not advisable, particularly if it exhibits concerning features like hardness and immobility. Providing a complete medical history, including any recent infections, trauma, or vaccinations, will be the starting point for the consultation.
Initial Examination and Imaging
The initial physical examination involves the doctor manually assessing the lump’s size, texture, and mobility to determine its characteristics. Based on this examination, the provider may order diagnostic imaging, which often begins with an ultrasound to visualize the internal structure of the lump and surrounding tissue. For women, a mammogram or breast magnetic resonance imaging (MRI) may also be necessary, as armpit lumps can sometimes be the first sign of breast cancer.
Biopsy for Definitive Diagnosis
If the imaging results remain inconclusive or if the lump appears suspicious, the definitive diagnostic tool is a biopsy. This procedure involves removing a small sample of tissue from the lump to be examined under a microscope by a pathologist. The biopsy determines the exact cause of the lump, conclusively distinguishing between a benign condition, an infection, or a malignancy.