Pancreatic mass

A pancreatic mass is any undifferentiated growth detected in the pancreas, usually on medical imaging. A number of terms used to describe abnormal masses (also known as tumors) in the pancreas. Masses can be described based on their physical characteristics, as defined by imaging studies, as solid (consisting of solid abnormal tissue) or cystic (cavities filled with mucus or fluid). Masses can also further be described based on their aggressiveness usually based on imaging and examination of their cells under the microscope as benign (no potential for turning into cancer), premalignant (some potential to turning into cancer) and malignant (cancerous). Masses involving the pancreas are being recognized more frequently, in part because of the growing use of radiology imaging. Many lesions found on the pancreas turn out to be benign “pseudocysts,” but a variety of harmless (benign) and malignant (cancerous) neoplasms (abnormal growths) can involve the pancreas and a multidisciplinary approach including good clinical history, imaging, and careful pathology is often needed to establish the correct diagnosis.^[1]

Signs and symptoms

The clinical history can often help establish the nature of a tumor involving the pancreas. For example, a history of alcoholism complicated by multiple episodes of pancreatitis (inflammation of the pancreas) suggests the possibility of a pseudocyst, the leakage and collection of pancreatic enzymes outside of the pancreas. By contrast, patients with painless jaundice (an abnormal yellowing of the skin and eyes often caused by blockage of the bile ducts) are more likely to have a pancreatic cancer. Blood tests can also point to the correct diagnosis. Patients with pseudocysts often have associated pancreatitis with elevated blood levels of the enzymes amylase and lipase, while patients with pancreatic cancer may have elevated levels of the cancer marker CA19-9.^[2]

Diagnosis

A number of different approaches can be used to visualize the pancreas. The most common include CT scan (computerized axial tomography), magnetic resonance imaging (MRI), positron emission tomography (PET), endoscopic ultrasound (EUS), and endoscopic retrograde pancreatography (ERCP).^[2] Each of these different imaging approaches has its own strengths and weaknesses. CT scanning is a widely available and an excellent modality to image the pancreas. MRI is a great method to visualize the pancreatic ducts, PET scanning can reveal the metabolic activity of a tumor, EUS requires slight sedation but provides excellent detail and biopsies can be performed at the same time, and ERCP can be used to visualize the duct system of the pancreas and stents (small tubes to re-establish the flow of secretions such as bile) can be placed during the ERCP procedure. The broad questions that clinicians try to answer using these various approaches include: 1) Is a mass present? 2) Is the mass solid or is it cystic (does it form spaces or holes)? 3) Is the mass confined to the pancreas or has it spread to involve other structures or other organs? 4) What is the most likely diagnosis for this patient’s tumor?

Pathology

Often called the gold standard, pathology can play a critical role in establishing the diagnosis of a mass or tumor involving the pancreas. Pathology refers to the examination of fluids and tissues removed from the body. This examination typically involves the examination of slides using a microscope. The tissues to be examined by pathology are removed by biopsy (small sampling) or completely removed surgically (resection). Individual cells in these tissues can be examined using techniques called “cytopathology” or “cytology,” or sections of the tissue can be examined using by a surgical pathologist. In general, pathologists try to determine if the cells present can account for the lesion seen on imaging, and if the cells from the lesion are harmless (benign) or malignant (cancerous). Pathologists have a variety of special stains, such as "immunohistochemistry" at their disposal in difficult cases.

Treatment

All of the information obtained in the medical history, imaging and pathological analyses are considered in determining the best management of a pancreatic mass. In general, most solid pancreatic masses are either malignant or have malignant potential. Therefore, most solid tumors are usually removed surgically. The management of pancreatic cyst is often much more complex since the majority of these types of tumors are benign and therefore do not require surgery. Some cysts are cancerous, and others, such as the intraductal papillary mucinous neoplasm (IPMN) are potentially precancerous.^[3]

The key in management of pancreatic cystic lesions is to avoid an operation in people who have “innocent” cysts while on the other hand not choosing to observe individuals with cysts that may harbor malignancy. This concept may seem simple, but in practice differentiating between these two groups requires experienced physicians. If surgery is to be performed for a mass this surgery should be done in a center with experienced pancreatic surgeons who perform many of these types of operations on a regular basis.^[4]

A multi-disciplinary team approach, involving the coordinated efforts of clinicians, radiologists and pathologists is often the best way to evaluate a tumor involving the pancreas.^[1]

References