Axillary lymphadenopathy is when you have swollen lymph nodes in the armpit. The swelling may occur as a result of an infection, a systemic (whole-body) disease, an autoimmune disorder, or certain cancers. Even a vaccination can sometimes cause swollen lymph nodes under the arm.

Axillary lymphadenopathy is not a disease but a symptom of a disease. It can occur on its own or with lymphadenopathy in other parts of the body, such as the groin or neck. The location, persistence, and severity of lymphadenopathy—along with accompanying symptoms—can provide clues about the underlying cause.

Learn more about the symptoms and causes of axillary lymphadenopathy as well as the various tests and exams used to diagnose the underlying cause of swollen lymph nodes. It also offers tips on how to manage symptoms of lymphadenopathy if they are causing you pain or discomfort.

Symptoms of Axillary Lymphadenopathy

Axillary lymphadenopathy, also known as axillary adenopathy, is characterized by swelling and inflammation of one or more of the 20 to 40 axillary lymph nodes in each armpit. The swelling may be unilateral (affecting one armpit) or bilateral (affecting both armpits).

Swollen axillary lymph nodes can range in size from a small pea to a large grape. The nodes may feel spongy or hard like a marble.

Symptoms of axillary lymphadenopathy may involve some or all of the following:

  • One or more lumps under the armpitSwelling, warmth, and rednessPain or tendernessBurning or tingling sensationsSwelling of the adjacent breast or armFatigueFeverTirednessJoint or muscle pain

Some people may have no notable symptoms and only realize their lymph nodes are swollen while showering or when undergoing a physical exam at their healthcare provider’s office.

Causes of Swollen Lymph Nodes in the Armpit

Lymph nodes are part of the lymphatic system, a whole-body network of vessels, fluids, and organs that play a central role in our body’s immune defense. The lymphatic system transports fluids (called lymph) through a network of vessels, carrying along waste products, abnormal cells, and foreign invaders like bacteria.

Along the route are clusters of lymph nodes that function as filters, trapping any substance or organism that it considers abnormal. If a foreign invader is trapped, the immune system will respond with inflammation (the body’s natural response to anything it considers harmful).

With inflammation, blood vessels will dilate (widen) to allow immune cells closer access to the site of the infection or injury. This, in turn, causes fluids to leak into surrounding tissues, resulting in local swelling, warmth, and redness.

Axillary lymphadenopathy is a sign that the lymph nodes of the armpit have trapped something harmful that the immune system is trying to destroy (mainly with defensive white blood cells known as lymphocytes).

There are many possible causes of axillary lymphadenopathy, some of which are benign (non-cancerous) and others of which are malignant (non-cancerous).

There are about 450 lymph nodes situated in clusters throughout the body. In addition to axillary lymph nodes, there are cervical lymph nodes in the head and neck, inguinal lymph nodes in the groin, mediastinal lymph nodes in the chest, and retroperitoneal lymph nodes in the abdomen among others.

Benign causes of axillary lymphadenopathy can be broadly categorized as follows:

  • Local infections, such as a staphylococcal skin infection on the arm or chest
  • Regional infections, such as strep throat that can cause lymphadenopathy in the neck and armpits
  • Systemic infections, like HIV and mononucleosis that can cause lymphadenopathy in many parts of the body
  • Granulomatous diseases, like tuberculosis and sarcoidosis that produce inflammatory clusters of cells (called granulomas) that can invade lymph nodes
  • Autoimmune diseases, like lupus and rheumatoid arthritis in which the immune system attacks normal cells, triggering inflammation and regional or systemic lymphadenopathy
  • Vaccinations, like measles and COVID-19 vaccines that can cause unilateral lymphadenopathy

Malignant causes of axillary lymphadenopathy include:

  • Breast cancer, typically when the cancer is locally advanced
  • Lymphoma, a group of cancers affecting the lymphatic system
  • Leukemia, a type of blood cancer
  • Metastatic cancer, meaning cancer that has spread from its original site (such as the thyroid, lungs, pancreas, ovaries, or gastrointestinal tract) to distant parts of the body, including the lymph nodes

Diagnosis

Axillary lymphadenopathy can usually be identified with a physical exam. Your healthcare provider may discover swollen lymph nodes during a routine checkup even if you have no symptoms.

To narrow the possible cause of lymphadenopahty, the healthcare provider will consider several factors, including:

  • Size of the lymph nodesNumber of swollen lymph nodesPain or tendernessLocation (unilateral vs. bilateral)Consistency (whether the nodes are hard or spongy)Matting (whether the nodes are stuck together or individual)Mobility (whether the nodes are movable or not)

Together, these clues may point to certain conditions and exclude others.

Lab Tests and Procedures

Based on the physical exam and a review of your medical history, your healthcare may order a battery of tests to narrow the underlying causes, including:

  • C-reactive protein (CRP): A blood test that detects generalized inflammation
  • Erythrocyte sedimentation rate (ESR): Another blood test that detects generalized inflammation
  • White blood cell (WBC) count: A blood test that can detect infection due to an elevated lymphocyte count
  • Imaging studies: Such as an X-ray, ultrasound, or computed tomography (CT) scan to indirectly visualize the lymph nodes
  • Lymph node biopsy: In which a sample of tissue is removed for inspection by a lab pathologist

Additional tests and evaluations may be ordered based on the findings and suspected causes.

Differential Diagnosis

Lumps and masses in the armpit don’t always indicate lymphadenopathy. Some may be benign growths unrelated to the lymphatic system, such as:

  • Lipomas: Benign tumors composed of mature fat cells
  • Epidermal inclusion cysts: Benign cysts usually found on the skin
  • Fibroadenomas: Benign, painless breast lumps that can extend to the armpit
  • Schwannomas: Benign tumors affecting the membrane covering of nerves cells

These conditions usually can be differentiated with imaging studies and other procedures, such as a type of biopsy known as fine-needle aspiration.

Axillary Lymphadenopathy Treatment

There is no specific treatment for axillary lymphadenopathy other than to treat the underlying cause. These may include treatments like antibiotics for bacterial infections, disease-modifying antirheumatic drugs (DMARDs) for autoimmune diseases, or chemotherapy, radiation, and surgery for cancer.

With that said, pain and swelling can be relieved with certain at-home treatments, like:

  • A cold compress to reduce pain and swelling
  • A heating pad to improve blood flow and aid with healing
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) like Aleve (naproxen) or Advil (ibuprofen) to reduce pain and inflammation

Summary

Axillary lymphadenopathy is the swelling of lymph nodes in the armpits. It can occur for many reasons, including infections, vaccination, autoimmune disorders, and cancer.

Axillary lymphadenopathy is not a disease but a symptom of a disease. The treatment is focused on resolving the underlying cause.

To identify the underlying cause, your healthcare provider may order lab tests and imaging studies based on a physical examination and a review of your symptoms and medical history.

Frequently Asked Questions

  • What do lymph nodes in the armpit do?
  • Lymph nodes in the armpit fight against infection and cancer. The same is true of your other lymph nodes, which can be found in the abdomen, neck, groin, and pelvis.
  • Learn More:
  • Definition and Function of Lymph Nodes
  • Can COVID vaccinations cause axillary lymphadenopathy?
  • Yes, and it’s relatively common. One study found that 44% of people who had breast imaging after a COVID shot had lymphadenopathy up to 43 weeks after vaccination. Talk to your imaging center about the best time to schedule your appointment.
  • Learn More:
  • Mammograms After COVID-19 Vaccination
  • Can allergies cause swollen lymph nodes in your armpit?
  • Allergies, including medication allergies, may lead to axillary lymphadenopathy. However, this is not a common sign of an allergic reaction.
  • Learn More:
  • Swollen Glands in Children

Lymph nodes in the armpit fight against infection and cancer. The same is true of your other lymph nodes, which can be found in the abdomen, neck, groin, and pelvis.

Yes, and it’s relatively common. One study found that 44% of people who had breast imaging after a COVID shot had lymphadenopathy up to 43 weeks after vaccination. Talk to your imaging center about the best time to schedule your appointment.

Allergies, including medication allergies, may lead to axillary lymphadenopathy. However, this is not a common sign of an allergic reaction.

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By Indranil Mallick, MD

 Indranil Mallick, MD, DNB, is a radiation oncologist with a special interest in lymphoma.