What is the significance of short lymph nodes?

From the Guidelines

Short lymph nodes are generally considered normal and do not typically have clinical significance on their own, with a short-axis size of less than 1 cm being a common threshold for normality 1. When evaluating lymph nodes, healthcare providers consider several factors, including size, location, consistency, and associated symptoms.

• Lymph nodes are considered normal when they are small, soft, non-tender, and mobile.
• Enlarged, firm, fixed, or tender lymph nodes may indicate infection, inflammation, or malignancy.
• The size, location, consistency, and associated symptoms are all important factors in determining whether lymph node findings require further investigation. Normal-sized or "short" lymph nodes are generally considered physiologic and part of healthy immune surveillance.
• If lymph nodes become persistently enlarged, painful, or are associated with unexplained symptoms like fever, weight loss, or night sweats, consultation with a healthcare provider is recommended for proper evaluation, even if the nodes were previously normal in size. According to the most recent evidence, lymph nodes greater than 1 cm in short axis are highly suspicious for metastatic disease, particularly if they are located in the hilar regions of the kidney or in the para-aortic or caval areas 1. However, it is also important to recognize that a significant percentage of metastatic lymph nodes will be less than 1 cm, and some authors suggest using a cutoff value of 0.7 cm to 0.8 cm in testicular cancer at the expense of reduced specificity 1. Overall, the clinical significance of short lymph nodes should be evaluated in the context of the individual patient's symptoms, medical history, and other diagnostic findings.

From the Research

Significance of Short Lymph Nodes

The significance of short lymph nodes can be understood by examining various studies that have investigated the role and characteristics of lymph nodes in different medical contexts.

• Lymph Node Size and Malignancy: A study published in 1997 2 found that the length of non-fatty lymph nodes is associated with malignant status, with lengths greater than 33 mm being a predictor of malignancy. However, the study also noted that benign and malignant lymph nodes cannot be distinguished from each other mammographically in most cases.
• Lymph Node Enlargement: Research from 2014 3 highlighted the importance of accurately distinguishing between benign lymph node enlargement and recurrent lymph nodes in patients with esophageal squamous cell carcinoma. The study demonstrated a high incidence of enlarged lymph nodes after chemoradiotherapy, with some cases being benign reactive lymph node enlargement.
• Normal Lymph Node Size in Children: A 2005 study 4 investigated the prevalence of enlarged mesenteric lymph nodes in children and found that a short-axis diameter of up to 10 mm can be considered a non-specific finding. The study suggested that a short-axis diameter of 8 mm might better define the upper limit of normal mesenteric lymph node size in children.
• Lymph Node Staging in Non-Small Cell Lung Cancer: A study from 2008 5 analyzed the accuracy of positron emission tomography-computed tomography (PET-CT) in lymph node staging for non-small cell lung cancer. The results showed that while PET-CT is superior to CT alone, its specificity and accuracy are lower in the presence of enlarged lymph nodes.
• Risk of Lymph Node Metastasis: More recent research from 2022 6 focused on the prognostic factors of small non-functional pancreatic neuroendocrine tumors and the risk of lymph node metastasis. The study identified tumor location, size, and grade as independent risk factors for lymph node metastasis and proposed a risk score system to predict the likelihood of metastasis.

Key Findings

• Lymph node size can be an indicator of malignancy, but distinguishing between benign and malignant nodes can be challenging.
• Lymph node enlargement can occur due to various reasons, including benign reactive changes or metastatic disease.
• The definition of normal lymph node size can vary depending on the population and context, such as in children.
• The accuracy of imaging techniques like PET-CT in lymph node staging can be influenced by the size of the lymph nodes.
• Certain factors, such as tumor characteristics, can predict the risk of lymph node metastasis in specific types of cancer.