For the diagnosis of pathologically enlarged nodes, information about normal node size is required. Commonly used metrics for lymph node measurement include the maximum and minimum axial diameters, and the ratio of these two values [8]. The shortest axial diameter appears to be a more useful parameter than the greatest axial diameter, although a different threshold should be used for each nodal station [5

The generally accepted size criterion for mediastinal lymph node enlargement (>10 mm along the short axis) has been applied to all patients when staging lymphoma or bronchogenic carcinoma [10.

Other authors use the following standard maximum normal short-axial diameters for nodal regions: region 7, 12 mm; regions 4 and 10R, 10 mm; and other regions, 8 mm. Maximum greatest axial diameters show wider variation, ranging from 10 to 25 mm [9].

Lymph node location and age must also be taken into account when evaluating lymph nodes in the pediatric chest. At least one enlarged lymph node was found in 96% of children, with subcarinal (69%), lower paratracheal (64%), and hilar (60%) nodes being most common. Up to 10 years of age, most lymph nodes are ≤7 mm in diameter. In older children, lymph nodes with short-axis diameters of up to 10 mm have been found [11].”