What CT and MRI findings can help distinguish benign from malignant lymph nodes?
Lymph nodes with a short axis diameter of <10 mm or with an oval shape are more likely to be benign in nature, whereas lymph nodes with a short axis diameter of ≥10 mm or with a spherical shape are more likely to be malignant in nature. However, these morphologic properties are nonspecific, as normal-sized lymph nodes may harbor malignancy and enlarged lymph nodes may be nonneoplastic in nature. Attenuation and signal intensity properties are also not accurate to differentiate between benign and malignant lymph nodes. Yet, malignant lymphadenopathy is more likely when there is associated anterior displacement of the abdominal aorta from the spine, lateral displacement of the ureters, or a history of known malignancy.