Axillary lymph nodes are small, bean-shaped glands located in the armpit area. These nodes play a significant role within the body’s immune system, acting as filters that trap foreign particles, waste products, and pathogens like bacteria and viruses. They also house immune cells that help fight off infections and diseases. Ultrasound is a non-invasive medical imaging technique that uses high-frequency sound waves to create real-time images of structures inside the body. This method allows medical professionals to visualize the axillary lymph nodes without using radiation. The sound waves bounce off tissues and return to a transducer, which then converts them into an image displayed on a monitor.
Purpose of Axillary Lymph Node Ultrasound
Axillary lymph node ultrasound is performed for several medical reasons. One primary purpose is in the staging of breast cancer, as it helps determine if cancer cells have spread from the breast to the nearby lymph nodes. This information is important for guiding treatment decisions. The procedure is also used to investigate a palpable lump or any other abnormality discovered during a physical examination in the armpit region.
An axillary lymph node ultrasound also monitors known cancer or checks for recurrence in patients who have previously undergone treatment. It can help assess changes in lymph nodes over time. The ultrasound also serves to evaluate unclear findings from other imaging tests, such as mammograms or magnetic resonance imaging (MRI). It provides a more detailed view of the lymph nodes, helping to clarify their appearance when other scans are inconclusive.
Performing the Ultrasound
Undergoing an axillary lymph node ultrasound is a straightforward and comfortable experience for the patient. Minimal preparation is required, with no fasting or dietary restrictions. Patients are positioned lying down on an examination table, often with their arm raised above their head for optimal access to the armpit area.
A clear, water-based gel is applied to the skin over the armpit. This gel helps the transducer glide smoothly and ensures good contact. The sonographer or radiologist moves a small, handheld device called a transducer across the skin, creating real-time images. The procedure is non-invasive and painless, with most scans taking approximately 15 to 30 minutes to complete.
Identifying Cancerous Features
During an axillary lymph node ultrasound, radiologists examine several visual characteristics to differentiate between benign and potentially malignant nodes. These include:
Size: Larger nodes, particularly those exceeding 1 cm in their shortest diameter, can raise suspicion, although size alone is not a definitive indicator of malignancy.
Shape: Benign lymph nodes maintain an oval or bean-like shape, while nodes that appear more rounded or spherical can be concerning.
Cortical thickness: The thickness of the outer layer, known as the cortex, is another feature. A cortical thickness greater than 3 mm is considered suspicious, especially if it appears irregular or asymmetrical.
Central fatty hilum: The presence or absence of a central fatty hilum is also noted; benign lymph nodes exhibit a bright, fatty center, and its displacement, compression, or complete absence can suggest malignant involvement.
Blood flow patterns: Radiologists also assess the blood flow patterns within the node, as abnormal or increased vascularity, particularly if it appears chaotic or penetrating the cortex, can be an indicator of malignancy.
Multiple suspicious nodes: The presence of multiple suspicious nodes clustered or grouped together in the armpit region can heighten suspicion for cancer spread.
These features serve as indicators that warrant further investigation, and their interpretation is correlated with the patient’s overall clinical history.
Next Steps After Findings
If an axillary lymph node ultrasound reveals features suspicious for malignancy, the next step involves obtaining a diagnosis through a biopsy. This procedure often involves an ultrasound-guided biopsy, where the ultrasound machine is used in real-time to precisely guide a needle into the suspicious lymph node. The two common types are fine needle aspiration (FNA) or core needle biopsy, both of which collect tissue samples for laboratory analysis. The collected tissue is sent to a pathology lab, where pathologists examine the cells under a microscope to determine if cancer cells are present.
Further imaging tests like an MRI or a PET (Positron Emission Tomography) scan may be recommended to gain a clearer visualization of the extent of disease or to aid in cancer staging. The findings from the ultrasound and any subsequent biopsy are discussed by a multidisciplinary team, which may include oncologists, surgeons, and radiologists. This collaborative approach helps formulate a comprehensive treatment plan tailored to the individual patient. Suspicious findings on an ultrasound do not automatically confirm cancer but necessitate these further investigations to establish a precise diagnosis and guide appropriate medical management.