Mass in the groin on CT is a common imaging finding. The groin is where the thigh meets the abdomen to the left and right side of center. The groin is often referred to as the inguinal region. A groin mass can often be felt, but at times is discovered as a surprise. Some causes of groin mass are benign cysts, while others may represent cancer.
One of the more common causes of groin mass on CT is a hernia. A hernia is a protrusion of the abdominal contents through a defect in the abdominal wall. Hernias in the groin can be composed of abdominal fat or bowel loops. They may or may not be symptomatic. Hernias are dangerous because the protruding bowel loop can cause a bowel obstruction or be squeezed hard enough to prevent blood flowing to it. This can lead to a dangerous condition called strangulation which needs prompt treatment.
Lymph nodes which become enlarged can cause a groin mass. Lymph nodes can enlarge from inflammation, infections, drugs or cancer. The larger the node, the more concerning it becomes for possibility of cancer. Often, a history of cancer will already be present. Inquiring about any infections in the tissues around the lymph node will be helpful to explain the enlargement. A tumor or abnormal growth can also cause a mass in the groin region.
A groin mass can be a result of an aneurysm or pseuroaneurym of the femoral artery which travels through the groin. A pseudoaneurysm can occur after a procedure where the femoral artery is punctured, like a heart angiogram. The vessel will will be injured and blood will leak into the adjacent tissues.
Cysts can form in the groin. These can be of various origin but are usually filled with fluid. Blood can accumulate in the groin after procedures and trauma and cause a mass to be seen on CT. An abscess or pocket of pus can form in the groin after certain procedures or infections. A testicle which is undescended to the scrotum can cause a mass in the groin.
Groin masses can therefore have many causes ranging from benign to needing urgent treatment. Groin masses are often diagnosed on CT based in their characteristic appearance. Some groin masses are left alone and benign while others need surgical treatment like hernias. The history and appearance on CT also helps with identifying the cause of the groin mass.