Approach to pancreatic masses: Clinical sciences

Pancreatic masses are either cystic or solid lesions, and can be benign or malignant. Often, these masses are found incidentally during abdominal imaging performed for an unrelated reason.

Cystic pancreatic lesions are more commonly found, and fall into three categories: non-neoplastic pancreatic cysts, pancreatic cystic neoplasms, and inflammatory fluid collections. Solid masses are less common and include tumors of the exocrine pancreas, such as adenocarcinoma and benign adenomas; as well as pancreatic neuroendocrine tumors.

When a patient presents with a chief complaint suggesting a pancreatic mass, your first step is to obtain a focused history and physical examination. Patients often report vague symptoms like abdominal pain that radiates to the back. In some cases, they might have a history of chronic pancreatitis. The physical exam is typically unremarkable, but depending on the size and location of the mass, you might find tenderness in the upper abdomen.

If you suspect a pancreatic mass, your next step is to order a CT scan of the abdomen and pelvis. A CT scan can help you determine if the mass is cystic, solid, or indistinct. Understanding these key features will help you narrow down your differential further.

Let's start our discussion with pancreatic cysts. For these patients, your next step is to order labs like liver function tests and a basic metabolic panel, as well as a more detailed CT scan of the pancreas, known as the triphasic pancreatic protocol. You may also consider an MRI.

Alright, first up we have non-neoplastic pancreatic cysts or NNPCs for short. Most patients are asymptomatic. In some cases, history might reveal associated risk factors, such as cystic fibrosis or polycystic kidney disease. The physical exam is usually unremarkable with a soft, non-tender abdomen; and labs are often normal, although LFTs might be elevated in some cases.

On CT scan with pancreatic protocol, you can expect to find a single, well-defined, non-enhancing, unilocular cyst with no solid elements, no septa, and no communication with the pancreatic duct. These features are characteristic of NNPCs, which includes retention, true, or simple cysts.

Okay, let's move on to another type of pancreatic cyst called pancreatic cystic neoplasms, or PCNs for short. Although these are benign lesions, they can cause mass effect as they grow in size. Patients typically report unintended weight loss, abdominal pain, nausea, vomiting, steatorrhea, new-onset diabetes, and jaundice. You can expect to find a non-tender abdomen on examination. Labs are often normal, although some patients may have elevated LFTs and bilirubin levels.

On CT scan, you will likely see a cyst that’s round, well-encapsulated; unilocular or septated; with wall calcifications. Additionally, most lesions may communicate with the pancreatic ductal system causing a dilated pancreatic duct. With these findings, consider a neoplastic cystic mass.

To confirm the diagnosis, your next step is to obtain a fine needle aspiration, or FNA, of the cystic fluid. Aspiration of non-viscous fluid that contains mucin or glycogen with low levels of amylase and carcinoembryonic antigen, or CEA, is diagnostic of PCNs.

Here’s a clinical pearl! There are three main types of PCN: intraductal papillary mucinous neoplasm or IPMN; mucinous cystic neoplasm; and serous cystadenoma. Although these are all benign, certain subtypes like main-duct intraductal papillary mucinous neoplasms carry higher malignant potential. For that reason, the majority of these subtypes are surgically resected.

Alright, let’s go back and talk about our final type of pancreatic cystic lesions, inflammatory fluid collections. These are walled-off collections of fluid that tend to form as a complication of repeated episodes of pancreatic inflammation. So, history might include chronic pancreatitis, alcohol use disorder, or both. Symptoms can be similar to pancreatitis, such as abdominal pain, nausea, vomiting, and steatorrhea. Jaundice might be present in severe cases. In these patients, your physical examination will reveal abdominal tenderness and distention, and labs often show elevated LFTs.

The CT will likely show an encapsulated, fluid-filled collection adjacent to the pancreas. If these are your findings, consider an inflammatory cystic mass and order an FNA to confirm.