Pancreatic Cystic Lesion on CT
A common finding is a pancreatic cyst or cystic lesion on CT of the abdomen done for a variety of reasons. Usually an incidental finding, meaning they are often not the cause of the symptoms that the CT scan was ordered for. These can range in size from barely visible to large cystic masses. The main possibilities are usually a cystic neoplasm/tumor or pseudocyst. MRI of the abdomen is the best test to further evaluate these and will often be recommended for follow up.
Pseudocysts are one of the possibilities when a cyst or cystic lesion of the pancreas are discovered on CT of the abdomen. These look like cysts and are filled with blood, pancreatic enzymes and necrotic or dead tissue. Patients will often have a history of alcohol abuse, gallstones, abdominal trauma or pancreatitis. These sometimes occur separate from the pancreas or even in more distant locations like the chest. These are not tumors and do not have the potential to turn cancerous.
The other possibility for pancreatic cysts or cystic lesions is a tumor. Some of these cystic tumors are premalignant. This means that there is a possibility that they transform into a cancer that can spread and cause sickness and death. Most cysts identified on CT scan of the abdomen will be further evaluated on MRI of the abdomen which allows a more detailed evaluation and possible specific diagnosis.
Cystic lesions of the pancreas can sometimes be distinguished on MRI by their imaging appearance. Some of the tumors have features which allow a specific diagnosis, like communication with the pancreatic duct. Another helpful clue is the age and sex of the patients as some of the tumors have a tendency to develop in women who are middle aged or elderly. Many are premalignant and need close follow and workup up according to guidelines published by radiology and gastroenterology societies.
These cystic tumors are most commonly serous cystic neoplasms, mutinous cystic neoplasms, and intraductal papillary mucinous neoplasms. Often they can not be distinguished on imaging and instead followed closely with serial imaging studies for growth.
Some of the larger or more suspicious cystic lesions will undergo an invasive procedure called an endoscopic ultrasound and fine needle aspiration. In these cases, a specially trained gastroenterologist will attempt to draw fluid from the cyst to get a better idea of what the diagnosis is. More suspicious lesions may undergo surgery for resection.
Cystic lesions of the pancreas can in rare circumstances represent pancreatic cancer which has become necrotic or the tissue has mostly died within it. This is because the tumor outgrows it’s blood supply. It is usually not difficult to say that we’re dealing with an aggressive cancer because these are larger and have secondary findings which point to something aggressive. These are more infiltrative in appearance or not well defined like a cystic neoplasm. The tumor often extends outside the pancreas and there is spread to lymph nodes and organs such as liver.
In conclusion, cysts or cystic lesions of the pancreas are common incidental findings often found on CT scans of the abdomen. These are usually benign pseudocysts from pancreatitis or cystic tumors. An MRI of the abdomen will be recommended to further evaluate because this study allows a more detailed look.
Many times, a specific diagnosis will not be made on imaging. Because some are premalignant or can potentially become cancerous, close imaging follow up will be needed looking for growth or suspicious change in appearance. The more suspicious looking cystic lesions and the larger ones may undergo invasive testing or even surgery.