What Does a Lymph Node With a Fatty Hilum Mean on Ultrasound?

A lymph node with a fatty hilum is a node whose bright central area, called the hilum, is still visible on ultrasound. This is usually a reassuring feature, because normal lymph nodes often show it. A radiology review in Cancer Imaging describes a normal node as oval and frequently containing an echogenic (bright) fatty hilum.

This guide explains the report wording. It does not replace the radiologist's overall conclusion or your clinician's assessment, which also considers your symptoms, examination and history. If you have a lump that has not been scanned yet, see a clinician about it first.

A reassuring scan does not cover new or worsening symptoms. The NHS advises asking for an urgent GP appointment or getting help from NHS 111 if swollen glands come with great difficulty swallowing or breathing. In an emergency, call local emergency services.

Healthdirect Australia advises seeing a doctor urgently if swollen lymph nodes come with fever, night sweats, unexplained weight loss, or bruising or bleeding easily. Arrange a review, even after a reassuring report, if:

• The node is getting bigger, or has not gone down as your clinician expected. The NHS gives one week, and Healthdirect two weeks, as points to see a doctor.
• The node feels hard or does not move when pressed.
• A swollen gland is just above or below the collarbone.
• You have night sweats, a very high temperature or weight loss you cannot explain.
• For a child, they have trouble swallowing liquids or breathing, or seem very unwell. Get medical help straight away.

Lymph nodes are small parts of the immune system found throughout the body. They help the body recognise and fight germs. On ultrasound, a typical node has a darker outer rim, called the cortex, and a brighter centre, the hilum.

The Cancer Imaging review describes the hilum as a linear, bright structure that contains the node's blood vessels. Fat in this area reflects sound strongly, which is why it looks bright. Reports may call it a fatty hilum, an echogenic hilum or a preserved hilum. These usually mean the same thing.

Radiology reviews describe several features that usually go together in a normal or benign node:

• Oval or kidney-like shape, rather than round. One review notes that benign nodes are more likely to be oval.
• A visible bright fatty hilum.
• Blood flow entering through the centre (hilar or central vascularity) on Doppler.
• An even internal pattern and smooth outline.

Yes. Lymph nodes often enlarge when the body is fighting an infection. MedlinePlus states that infections are the most common cause of swollen lymph nodes. Healthdirect says swollen nodes usually mean the immune system is fighting an infection in the area.

MedlinePlus lists common infections that can make nearby nodes swell, such as colds and flu, ear infections, tonsillitis, dental problems, mouth sores and skin infections. It also notes that some medicines and the typhoid vaccine can cause swelling. Painful, sudden swelling is usually linked to injury or infection. Tell your clinician about any recent illness, vaccine or skin problem near the node, because this helps them interpret the scan.

These reactive nodes can look large by size rules alone. A 2026 Cancer Imaging review notes that reactive nodes may be considered abnormal by size criteria even though they reflect a normal response. The earlier review adds that size thresholds vary with the body area. This is one reason radiologists look at shape and hilum, not only measurements. Size limits used for children also differ; MedlinePlus describes a child's node as enlarged above 1 centimetre wide.

The reviews list features that can make a radiologist suggest further tests. These include:

• Loss of the bright fatty hilum.
• A more rounded shape. One review notes that a long-to-short axis ratio below 2 favours malignancy.
• Thickening of the cortex, irregular outline or an uneven internal pattern.
• Blood flow at the edges or in unusual patterns, rather than through the centre.
• Fluid-filled (cystic) or dead (necrotic) areas, which a 2026 review describes as the most specific signs of spread from a cancer.

Not on its own. It is a reassuring feature, and Healthdirect notes that only about 1 in 100 people with swollen lymph nodes, if any, is likely to have cancer. But imaging has limits. The 2009 review notes that ultrasound results can vary between operators, and that some normal-sized nodes can still contain cancer cells in people with known cancer.

That is why the radiologist's overall impression, your symptoms and any change over time matter more than one word in the report. If cancer is a concern, Healthdirect says a lymph node biopsy may be needed. Blood tests or other scans may also be used.

Bring the full ultrasound report, not only a portal summary. Useful questions include:

• What was the radiologist's overall conclusion about this node?
• Were any features other than the fatty hilum described as unusual?
• Is the size within what you expect for this area, and for my age?
• Do you think this node is reacting to an infection or another cause?
• Is a repeat scan, a blood test or any other check planned, and when?
• What changes should make me contact you before then?

On SameCase, patients and verified doctors share de-identified cases. Seeing how others described a report mentioning a fatty hilum, the follow-up they were offered and the questions they asked can help you plan your own questions.

Other cases cannot tell you what your node is or what will happen next. We suggest using them to prepare for your appointment, and leaving decisions to your own clinician.