Which shape best describes a normal axillary lymph node on ultrasound?

• A. Smooth
• B. Reniform shape
• C. Irregular
• D. Round

Answer: (B)

On ultrasound, a normal axillary lymph node tends to be elongated and kidney-shaped, described as reniform. This shape comes from the long axis being wider than the short axis and the node’s internal structure showing a preserved echogenic hilum with a thin cortex. This reniform (oval) silhouette is the typical, reassuring appearance of a normal node.

A round shape would suggest the node is more spherical, which is more concerning for pathology. An irregular contour would indicate an abnormal makeup of the surface, and a purely smooth description doesn’t specify the characteristic elongated outline seen in healthy nodes. So the kidney-shaped (reniform) appearance best matches a normal axillary lymph node on ultrasound.