The posterior margin of this node has a hazy, ill-defined margin. This finding is often seen after therapeutic radiation but may also be seen prior to treatment. This is not, on its own, sufficient evidence of Grade 1 iENE. Definitive invasion of the fat plane must be established.
Grade 0 (not Grade 2)
These two pathologic nodes abut, but there is a clear delineation between them. The borders of both nodes remain visible. Of note, although there is minimal loss of the fat plane between the two nodes, there is no loss of convexity or loss of the acute angle (arrowheads) at the point of contact.
Grade 0 (not Grade 1)
There is slight irregularity along the edge of this node, but it is not definitive, so this remains a Grade 0 node.
Grade 0 (not Grade 2)
This metastatic node is lobulated (arrow). Although this might be two nodes that have coalesced, it might also be lobulation of a single node. Even after confirmation in other planes of imaging, there was still not definitive evidence of coalescence. This scan might be reported as “probable iENE”, but it is not sufficient evidence for upclassifying neck nodes to Grade 2.
Grade 0 (not Grade 3)
The fat between the node and the SCM is absent. The anterior border of the muscle is distorted. However, the enhancement within the muscle itself remains normal. This scan might be reported as “probable iENE”, but it is not sufficient evidence for upclassifying neck nodes to Grade 3.
Grade 0 (not Grade 1 or Grade 3)
The SCM is stretched and distorted by this large node, but there is no loss of muscle volume or signal abnormality within the muscle itself. The node is well-defined and shows only equivocal infiltration of the surrounding fat along its posterior margin.
Grade 2 (not Grade 3)
Invasion of the internal jugular vein is sufficient for a designation of Grade 3 iENE. But in this case, the IJV (arrow) is compressed and displaced, not invaded. There is no evidence of tumor thrombosis. (Grade 2 iENE comes from the coalescent nodes (*), which was confirmed in other imaging planes, but this case is included in order to discuss the IJV.)
