What are the other Names for this Condition? (Also known as/Synonyms)

• Islet Cell Tumorlet of Pancreas
• Neuroendocrine Microadenoma of Pancreas
• Pancreatic Endocrine Microadenoma

What is Pancreatic Neuroendocrine Microadenoma? (Definition/Background Information)

• Pancreatic Neuroendocrine Microadenoma (pNEMA) is a biologically benign tumor in the hormone-producing cells of the pancreas, typically less than 0.5 cm in diameter. It is predominantly reported in older adults
• Although the tumor occurs in the endocrine pancreas, in the head, body and tail regions of the organ, pNEMA is classified as a non-functional neoplasm, and it does not produce enzymes
• Pancreatic Neuroendocrine Microadenoma may be associated with conditions, such as multiple endocrine neoplasia and von Hippel Lindau syndrome. No association of pNEMA has been reported with chronic pancreatitis
• Since the tumor is non-functional, the affected individuals are often asymptomatic and the diagnosis is often incidental. A healthcare professional decides the course of treatment, which may involve surgical excision of the tumor
• The prognosis for Pancreatic Neuroendocrine Microadenoma is positive in a majority of cases, since there is no evidence to suggest transition to malignancy

The pancreas is an important organ of the digestive system.

• Functionally, the pancreas can be divided into 2 parts, namely:
  • Exocrine pancreas, which produces digestive enzymes, and constitute about 95% of this important organ
  • Endocrine pancreas, which secretes hormones such as insulin, glucagon, gastrin, and somatostatin. Insulin and glucagon regulate sugar levels in blood

Pancreatic tumors (benign and malignant) can arise from both the exocrine and the endocrine components of the organ. Most endocrine tumors are benign and develop at a slower rate than exocrine tumors.

• Based on the anatomy of the pancreas, it can be divided into 3 main parts, namely the:
  • Head
  • Body and
  • Tail

Pancreatic tumors can affect the head, body, and tail region of the pancreas. Some tumors can affect one region of the pancreas more than the other.

Who gets Pancreatic Neuroendocrine Microadenoma? (Age and Sex Distribution)

• Pancreatic Neuroendocrine Microadenoma may occur in individuals of all races and ethnicities. Both genders are susceptible to the condition
• Individuals of all ages may be vulnerable to the tumor, but older adults are more prone to develop pNEMA
• However, if the condition is associated with multiple endocrine neoplasia or von Hippel Lindau syndrome, the tumors may occur at a younger age in those affected

What are the Risk Factors for Pancreatic Neuroendocrine Microadenoma? (Predisposing Factors)

The following are some known risk factors for Pancreatic Neuroendocrine Microadenoma:

• Age: Older individuals are more likely to develop the tumor
• Individuals with certain inherited disorders such as:
  • Von Hippel-Lindau (vHL) syndrome
  • Multiple endocrine neoplasia type 1 (MEN 1)

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Pancreatic Neuroendocrine Microadenoma? (Etiology)

The exact cause of Pancreatic Neuroendocrine Microadenoma is not known.

• The condition may develop sporadically, although such tumors are reported to have a distinct molecular signature. This type of benign tumors reportedly occurs in up to 10% of the pancreas
• Certain conditions caused by gene mutations may predispose an individual to Pancreatic Neuroendocrine Microadenoma. These may include:
  • Von Hippel-Lindau syndrome, which occurs owing to genetic mutations in the VHL gene. This syndrome may lead to an increased risk of pancreatic cancer and ampullary carcinoma
  • Multiple endocrine neoplasia type 1 (MEN 1), caused by genetic mutations in the MEN1 gene. This condition may increase the risk of tumors in the parathyroid gland, the pituitary gland, and the islet cells of the pancreas

What are the Signs and Symptoms of Pancreatic Neuroendocrine Microadenoma?

Pancreatic Neuroendocrine Microadenoma is less than 5mm in diameter and typically does not present with symptoms. Some features of pNEMA include:

• The tumor is usually present as a single mass of less than 5 mm in diameter
• When associated with multiple endocrine neoplasia and von Hippel Lindau syndrome, multiple tumors may be present
• The tumors are not functional, and do not cause symptoms of excess hormone production
• Symptoms of the underlying genetic disorders (if any) may be observed

How is Pancreatic Neuroendocrine Microadenoma Diagnosed?

Owing to its small size and non-functional nature, the diagnosis of Pancreatic Neuroendocrine Microadenoma is often incidental. The following methods may be employed to confirm pNEMA and rule out any malignancy (pancreatic cancer):

• Physical examination and medical history evaluation: The diagnosis begins with a thorough physical examination and evaluation of complete medical history. During a physical exam, the overall health status and symptoms (such as pain, loss of appetite, and weight loss) of the affected individual are checked
• Computerized tomography (CT) scan of the pancreas: With this radiological procedure, detailed three-dimensional images of structures inside the body are created. 
• Magnetic resonance imaging (MRI) scan of the pancreas: An MRI scan uses magnetic fields that create high-quality pictures of certain body parts, such as tissues, muscles, nerves, and bones. These high-quality images may indicate to a physician if any pancreatic cancer is present
• In addition, there are certain specific types of MRI scans that can be used in an individual who may have pancreatic cancer. Such radiological procedures include:
  • MR cholangiopancreatography (MRCP): It is a noninvasive test that uses a powerful magnetic field to produce images of soft tissues, bones, organs, and all other internal body structures
  • MR angiography (MRA): It is a noninvasive test that uses a powerful magnetic field to evaluate the blood vessels
• Endoscopic ultrasound (EUS): This is a minimally invasive procedure recommended for individuals who are suspected to have pancreatic cancer. An ultrasound device is inserted through a thin tube (called endoscope) down the stomach and into a part of the small intestine. It uses high-frequency sound waves to generate detailed images of the pancreas
• Endoscopic retrograde cholangiopancreatography (ERCP): A procedure used when an individual has developed symptoms of pancreatic cancer. An ultrasound device is inserted through a thin tube (called endoscope) down the stomach and into the first part of the small intestine. A dye is injected into the pancreas and bile ducts. The movement of the dye is followed through a series of images. A small tissue sample (biopsy) can be collected during this procedure
• Tissue biopsy: A tissue biopsy of the cyst (including the fluid inside the cyst) or mass is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
  • Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies, to assist in the diagnosis
• The tissue for diagnosis can be procured in multiple different ways, and they include:
  • Fine needle aspiration (FNA) biopsy of the pancreatic tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
  • Core biopsy of the pancreatic tumor
  • Open biopsy of the pancreatic tumor
  • Endoscopic retrograde cholangiopancreatography
• Somatostatin receptor scintigraphy (SRS): This test involves injecting radioisotope materials that attach to proteins on the tumor cells and gives out gamma rays, which are then detected by gamma cameras. This information is used to produce images that are helpful in diagnosing pancreatic neuroendocrine tumors (NETs)
• Positron emission tomography (PET): A PET scan is a nuclear medicine imaging technique that generates three-dimensional images to show how tissue and organs are functioning. A small amount of radioactive material may be injected into a vein, inhaled or swallowed. A PET scan is also helpful in detecting recurrences, or if any metastasis (to the surrounding lymph nodes of the pancreas) has occurred

A number of blood tests can also be helpful in ruling out pancreatic tumors that secrete hormones. These tests are primarily conducted to check levels of the following hormones:

• Insulin 
• Somatostatin 
• Glucagon 
• Gastrin 
• Vasoactive intestinal peptide (VIP)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Pancreatic Neuroendocrine Microadenoma?

Pancreatic Neuroendocrine Microadenoma is benign and less than 0.5 cm in diameter. No associated complications have been reported for this type of tumor.

How is Pancreatic Neuroendocrine Microadenoma Treated?

If deemed necessary, Pancreatic Neuroendocrine Microadenoma is treated by surgical excision, based on the healthcare provider’s assessment.

How can Pancreatic Neuroendocrine Microadenoma be Prevented?

Presently, there are no methods or guidelines available for the prevention of Pancreatic Neuroendocrine Microadenoma. However, taking steps to modify certain behavioral/lifestyle choices may help decrease the risk of its formation. These measures include:

• Smoking cessation: Smoking is the most significant risk factor associated with all types of pancreatic cancer. 20% to 30% of all pancreatic cancers develop due to smoking
• Physical activity: Obesity increases the risk for pancreatic cancers due to increased levels of inflammation in the body, which negatively impacts the overall immunity. Individuals, who participate in a modest amount of physical activity, may decrease their risk
• Adequate consumption of fruits and vegetables: A healthy diet, low in saturated fats and rich in many fruits and vegetables, may help decrease one’s risk for pancreatic cancer

What is the Prognosis of Pancreatic Neuroendocrine Microadenoma? (Outcomes/Resolutions)

Pancreatic Neuroendocrine Microadenoma is a benign condition with no evidence of transition to malignancy. The prognosis for pNEMA is typically excellent.

Additional and Relevant Useful Information for Pancreatic Neuroendocrine Microadenoma:

• It is estimated that the average lifetime risk of developing pancreatic cancer is about 1 in 67 (1.5%)
• Individuals can reduce their risk of developing pancreatic cancer through lifestyle or behavioral changes