Lymph Node Assessment

Diagnostic Criteria

• Nodes measuring 1.0-1.5 cm in short axis are considered abnormal only if the long axis exceeds 1.5 cm, as per the American Society of Clinical Oncology 1
• Nodes smaller than 1.0 cm in short axis are not considered abnormal for relapse or progressive disease, as per the American Society of Clinical Oncology 1
• A lymph node is considered enlarged when its short-axis diameter exceeds 10 mm, with specific size thresholds varying by anatomical location, as supported by the American College of Radiology and the National Comprehensive Cancer Network 2, 3, 4

• The following size thresholds are used to guide management decisions:

  Location	Size Threshold
  Mediastinal lymph nodes	>10 mm in short axis [4]
  Mediastinal lymphadenopathy	15 mm in short axis [4, 5]

• Measurable node criteria are defined as a long diameter greater than 1.5 cm, according to the Lugano Classification 2, 3, 1
• Target lesions are defined as lymph nodes with a long diameter greater than or equal to 15 mm, and nodes 10-14 mm are considered abnormal but not target lesions, as defined by the American College of Radiology 3
• Nodes greater than 10 mm in short axis are considered abnormal, but this alone is not definitive for malignancy, and nodes greater than 15 mm are more likely to be pathologic, as reported by the American College of Radiology 4
• Nodes greater than 25 mm are almost always pathologic, and normal-sized nodes may still contain malignancy, especially in lymphoma, as supported by the National Comprehensive Cancer Network 2, 4

Referral and Consultation

• Lymph nodes greater than 15 mm in short axis warrant specialist referral, and consideration of additional factors beyond size, including distribution pattern, internal characteristics, clinical context, and FDG avidity on PET-CT if available, as recommended by the National Comprehensive Cancer Network and the American College of Radiology 2, 4, 6, 7
• A patient with suspected mediastinal lymphadenopathy should be referred to a thoracic oncologist or pulmonologist with expertise in interventional pulmonology for further management, as recommended by the National Comprehensive Cancer Network 6, 7
• Hematologist-oncologist should be consulted when there is a strong clinical suspicion of lymphoma, as suggested by the American College of Radiology and the National Comprehensive Cancer Network 4, 8

Diagnostic Procedures

• Excisional lymph node biopsy is generally preferred for suspected lymphoma, according to the National Comprehensive Cancer Network 8
• EBUS-TBNA has high sensitivity and specificity for mediastinal lymph node assessment, with a pooled diagnostic accuracy of 68.7% for lymphoma diagnosis, as reported by the American College of Chest Physicians 6, 9
• Contrast-enhanced CT is recommended for comprehensive staging, as suggested by the American College of Radiology 4
• PET-CT is the preferred modality for suspected lymphoma or other FDG-avid malignancies, offering advantages such as detecting metabolically active disease in normal-sized nodes, as reported by the American College of Radiology and the National Comprehensive Cancer Network 2, 4, 10
• Ultrasound-guided FNA should be performed for palpable lymph nodes ≥1.5 cm in short axis or with suspicious features, and surgical excisional biopsy should be considered when FNA results are non-diagnostic or inconclusive, or when lymphoma is strongly suspected, as recommended by the American College of Radiology and the National Comprehensive Cancer Network 4, 11, 12

Management and Follow-up

• If biopsy confirms carcinoma, continue with thoracic oncology management; if biopsy confirms lymphoma, add hematology-oncology to the team; if biopsy is non-diagnostic, specialist will determine need for additional procedures, as recommended by the National Comprehensive Cancer Network 6, 7
• Ensure the IR team is aware of the need for sufficient tissue for molecular testing and flow cytometry if lymphoma is suspected, as recommended by the National Comprehensive Cancer Network 7