Lymph nodes are small, oval or bean-shaped structures found throughout the body that function as filters for the immune system. They trap bacteria, viruses, and abnormal cells, playing a key role in fighting infection and disease. On ultrasound, normal lymph nodes typically appear as small, oval, hypoechoic structures with a bright echogenic center called the fatty hilum. Abnormal lymph nodes may appear rounded, enlarged, lacking a hilum, or with irregular cortical thickening. Sonography of lymph nodes is commonly performed in the neck, axilla, and groin regions to evaluate for infection, lymphoma, or metastatic disease. Ultrasound can also guide needle biopsy of suspicious nodes.
Sonography Term