Lymph node enlargement | Radiology Reference Article | Radiopaedia.org (2025)

Lymph node enlargement(rarely lymphadenomegaly) is often used synonymously with lymphadenopathy, which is not strictly correct as lymphadenopathy refers to not only size enlargement but pathological change in shape and/or morphology ¹⁰.

Terminology

Lymphadenopathy (or adenopathy)is, if anything, a broader term than lymph node enlargement, referring to any pathology of lymph nodes, not necessarily resulting in increased size; this includes an abnormal number of nodes or derangement of internal architecture (e.g. cystic or necrotic nodes). In addition, an increase in size is not always pathologic; some nodes are bigger than others normally (e.g. cf.jugulodigastric nodes with mesenteric nodes), and reactive nodes are a healthy response and do not imply pathology of the node itself.

There are approximately 600 lymph nodes, of which only some are available to direct palpation. Only some nodes (including neck, axilla and groin) should ever be normally palpable, and when they are,they should be soft and non-tender.

Pathology

Etiology

There are many causes of lymph node enlargement, which include:

• infective (acute suppurative)

• reactive

  • follicular hyperplasia

  • paracortical hyperplasia

  • sinus histiocytosis

  • granulomatous

• neoplastic

• drug-induced:e.g. cyclosporine, phenytoin, methotrexate

• lipid storage diseases

• HIV related: HIV lymphadenopathy⁸

• IgG4-related sclerosing disease⁷

Radiographic features

The upper limit in size of a normal node varies with location, and the size cut-off used depends on the desired sensitivity and specificity.

Measuring short axis diameter best represents the size of the lymph node in CT imaging ⁹.

Cervical lymph nodes

See the article:cervical lymph node metastasis (radiologic criteria).

Mediastinal lymph nodes

In general, 10 or 15 mm is considered the upper limit for normal nodes (short axis diameter) depending on the clinical scenario ^3-5,10. This does not, of course, take into consideration the fact that all nodal metastases must start at microscopic size, and thus using only size criteria will miss micrometastases. In the setting of lung cancer staging a sensitivity of 0.83 and a specificity of 0.82 are quoted for CT ⁵.

See the article:mediastinal lymph node enlargement.

Mesenteric lymph nodes

Mesenteric nodes are increasingly visualized as a result of multidetector volume acquisition and are most easily seen on coronal reformats.

Although 3 mm has previously been used as the upper limit for the short axis diameter of mesenteric lymph nodes, up to 39% of healthy normal patients have larger nodes than this. As such a figure of 5 mm is considered normal ⁶.

See the article:normal mesenteric lymph nodes.

See also

• differential diagnosis of high attenuation lymphadenopathy

• differential diagnosis of low attenuation lymphadenopathy

• bilateral hilar lymph node enlargement

• periportal lymphadenopathy (differential)

• mesenteric adenitis