Imaging description

The superior diaphragmatic (or cardiophrenic or epicardiac) lymph nodes are in the mediastinum, but are routinely included on the upper slices of abdominal CT or MRI studies because they lie on the superior surface of the diaphragm in the fat adjacent to the heart. They are divided into anterior (paracardiac) and lateral (juxtaphrenic) groups [1,2]. The anterior group lies posterior to the lower sternum. The lateral group abuts the entrance of the phrenic nerve into the diaphragm, adjacent to the inferior vena cava on the right and the cardiac apex on the left. The normal superior diaphragmatic lymph nodes are usually small and often not visible by CT imaging. Pathological enlargement is generally defined as a short axis diameter greater than 5 mm [2, 3], although some use a short axis threshold of 8 or 10 mm [4, 5]. Enlarged superior diaphragmatic nodes are seen as nodular soft tissue structures lying just superior to the diaphragm and posterior to the sternum, adjacent to the cardiac apex, or abutting the supradiaphragmatic inferior vena cava (Figure 2.1).

Importance

The superior diaphragmatic lymph nodes receive lymph from the peritoneal cavity and the anterosuperior part of the liver. Enlargement of these nodes may be seen in:

Liver disease. In practice, cirrhosis and chronic hepatitis [6] are probably the commonest causes of superior diaphragmatic adenopathy. In chronic hepatitis, the degree of nodal enlargement (but not the level of serum liver enzymes) correlates with disease severity on biopsy [7].

Peritoneal disease. The principal peritoneal cause of superior diaphragmatic adenopathy is ovarian cancer. In general, studies of these nodes do not have a histopathological standard of reference because these nodes are not easily accessible for tissue sampling and outcome is used as an alternative endpoint.