Terminology for Adjacent Mediastinal Lymph Nodes in Lung Cancer
The term you're looking for is "matted lymph nodes" or "mediastinal infiltration" when two or more lymph nodes are fused together side-by-side in lung cancer staging.
Key Definitions from Staging Guidelines
Mediastinal infiltration occurs when abnormal tissue in the mediastinum does not have the appearance and shape of distinct lymph nodes but instead has an irregular, amorphous shape where multiple nodes are matted together to the point that the boundary between them is obscured, making it difficult to distinguish discrete nodes and impossible to measure their individual sizes 1. This typically indicates extensive extranodal spread of tumor and may progress to the point where mediastinal vessels and other structures are partially or completely encircled 1.
Clinical Significance
- When lymph nodes are matted together in this fashion, the presence of mediastinal involvement (stage III disease) is generally accepted based on imaging alone 1
- The primary clinical goal in these cases shifts from staging confirmation to obtaining tissue by the easiest approach to distinguish between small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) 1
- This represents radiographic group A in the staging classification system, where discrete lymph nodes can no longer be discerned or measured due to mediastinal infiltration that encircles vessels and airways 1
Contrast with Discrete Lymphadenopathy
This differs from discrete nodal enlargement (radiographic group B), where individual lymph nodes remain visible on CT scan and are defined well enough that their size can be measured (typically >1 cm short-axis diameter) 1. In discrete enlargement, mediastinal nodal involvement is suspected but must be confirmed through tissue sampling 1.