Identifying an Abdominal Mass on Radiographs
by Allison Zwingenberger on April 24, 2007Localizing the mass
If you see an obvious mass, the first step is to determine what quadrant of the abdomen it is in. Right cranial? Caudal midline? Mid-abdomen? When you narrow it down, you can make a mental list of the organs present in that area. For example, the right cranial quadrant contains liver, GI, and pancreas, and the right kidney and adrenal are in the retroperitoneal space in this area.What other organs are dispaced and where?
The next thing to do is to see what organs are being displaced by this mass. You have a mental picture of where the organs should be, so check to see if any are out of place in that region. You have a right cranial quadrant mass, and notice that the duodenum is displaced laterally, and the pylorus is displaced medially, leaving a widened gastroduodenal angle. What lives between the duodenum and the pylorus? The pancreas. So a pancreatic mass would be your top differential.[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]
Take a look at this radiograph. There is a mass located between the fundus of the stomach and the left kidney. The left kidney is displaced caudal to its normal position. The mass is located in the left cranial quadrant of the abdomen, in the area of the proximal extremity of the spleen. Organs normally present in the left cranial quadrant are stomach, left kidney, left adrenal, spleen, and pancreas. Which one could displace the left kidney caudally? A left adrenal mass tends to rotate the cranial pole of the kidney laterally, and the pancreas is a bit more ventrally located. Another vital clue: the normal stomach and kidney are visible, but a normal proximal extremity of the spleen is not. The spleen is most likely the cause of the mass.Indistinct abdominal masses
Sometimes the mass itself is not clearly visible, and you just see the mass effect, or the organs displaced by the mass. It looks like an area of poor detail with increased soft tissue opacity, and you can see that organs are moved away from it. Just use the same technique to narrow down the organs that it could be originating from.Generalized organ enlargement can cause the same signs
The same principles apply with generalized organ enlargement. Enlarged organs will displace other neighboring organs away from them, and this can help you to confirm that an organ is enlarged. Think of hepatomegaly changing the gastric axis.Check for the silhouette of the normal organ
Finally, if you think it’s originating from a particular organ, check to see if you see that normal organ. If there is a mass in the distal extremity of the spleen, you will probably not see the normal triangle of spleen caudal to the liver.
Determining the origin of an abdominal mass:*localize it to a quadrant of the abdomen*determine what organs are in that quadrant*look to see what organs are displaced (and where)*check to see if you see the normal silhouette of that organ*make your list of differential diagnoses