What is Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas?
Solid pseudopapillary epithelial neoplasms (SPEN), also known as tumors of the pancreas, are quite rare. They were first recognized by Dr. Virginia Kneeland Frantz back in 1959. These tumors have gone by many names in the past, such as Frantz tumors, Hamoudi tumors, and papillary-cystic tumors. Even though these tumors were initially considered harmless, they are now classified as low-grade malignant, or cancerous tumors. However, they spread slowly and most people with these tumors have a high chance of survival.
These tumors are usually observed in young women. However, it does not mean that they cannot occur in men, children, or older people. In adults, they are more often found in the middle or the tail-end part of the pancreas. But in children, they usually appear at the head of the pancreas, or the part closest to where the stomach is.
Patients don’t often experience noticeable symptoms for a long time, and by the time they start to feel something is wrong, the tumors have typically become quite large. In more rare cases, SPENs can spread to nearby organs or even far-off parts of the body. That’s why being able to correctly and quickly diagnose this condition is crucial for minimizing any potential complications and ensuring a better chance of a positive outcome for the patient.
What Causes Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas?
The exact cause of SPENs, an unusual type of pancreatic tumors, is still unknown. However, most evidence points towards the possibility that they originate from very versatile cells called pluripotent cells. These cells are a part of the genital ridges in the early stage of embryo development. They stick to the pancreas, thus becoming a possible source for SPENs. Several factors support this theory, including the distribution of this condition among sexes and different age groups, the lack of pancreatic markers, and the presence of sex hormone receptors in these tumors. Interestingly, some SPENs have been observed to shrink after menopause, which leads credibility to this theory.
Most SPENs seem to carry mistakes in the CTNNB1 gene, which codes for a protein named ß-catenin. This results in an excessive accumulation of this protein. Moreover, a rare association has been documented between SPENs and a condition called familial adenomatous polyposis. The link between the two might be due to disruption of a gene called APC, which, in turn, stimulates a pathway related to ß-catenin. However, these are theories based on current knowledge and further research is needed to fully understand SPENs.
Risk Factors and Frequency for Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
Solid pseudopapillary neoplasms, also known as SPENs, make up 1% to 2% of all exocrine pancreatic lesions and about 5% of cystic pancreatic lesions in adults. In children, SPENs represent between 6% and 17% of all pancreatic tumors. There’s been a significant increase in these types of tumors within the last 20 years, which could be due to better imaging and diagnostic techniques. SPENs are more common in females, with a ratio of 10 females for every male. They can be diagnosed in anyone from 8 to 67 years old, but the average age of diagnosis is 28.5 years. For men, the diagnosis typically happens around 18.5 years old.
- SPENs make up 1% to 2% of all exocrine pancreatic lesions and about 5% of cystic pancreatic lesions in adults.
- In children, SPENs represent 6% to 17% of all pancreatic tumors.
- There’s been a 7-fold increase in these types of tumors within the last 20 years.
- SPENs are more commonly found in females, with a ratio of 10 females for each male.
- People diagnosed with SPENs range in age from 8 to 67, and the average age at diagnosis is 28.5 years.
- For men, the diagnosis typically happens around 18.5 years old.
Signs and Symptoms of Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
Solid pseudopapillary neoplasms (SPENs) are slow-growing tumors that don’t show any signs or symptoms for a long period. More often than not, these tumors are discovered accidentally during routine physical exams or imaging studies for other health issues. If symptoms do occur, they are nonspecific and result from the SPEN pressing against nearby organs.
Common symptoms might include:
- Abdominal pain or discomfort
- Diarrhea
- Nausea
Rare symptoms could be jaundice or a blockage at the outlet of the stomach, depending on where the SPEN is located. Importantly, no hormonal imbalances have been linked to these tumors. SPENs rarely become malignant. If they do turn cancerous, the most common place for the cancer to spread is the liver. Other potential places for spread are nearby lymph nodes, abdominal tissues called the mesentery or omentum, and the peritoneum (the membrane lining the abdomen).
Testing for Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
Potential pancreatic tumors known as SPENs can sometimes be found during a physical exam but it’s challenging to make a certain diagnosis without more detailed testing due to the various other conditions it could be. Imaging tests such as computer tomography (CT) scans or magnetic resonance imaging (MRI) can create detailed pictures of the pancreas to help identify if a SPEN is present.
During a CT scan, SPENs often show up as thick-walled structures encapsulated within the pancreas, with a mix of solid and cystic (fluid-filled) components. One thing that sets SPENs apart from other pancreatic tumors is that they will absorb a special dye given during the CT scan at the same rate as the nearby pancreatic tissue.
However, MRI scans are considered to be more effective when diagnosing SPENs. In an MRI scan, SPENs display mixed signal intensity – meaning they appear in varying shades of brightness – on T1-weighted imaging and are highly bright on T2 weighted images. The tumor capsule shows up as a thin, darker rim. Angiographies, which are imaging tests that look at your blood vessels, can provide even more information about the SPEN and its relation to surrounding tissues. This can be crucial when deciding whether the tumor can be surgically removed.
While imaging tests provide valuable information, a preoperative pathology diagnosis is the gold standard for diagnosing pancreatic tumors. This involves taking a sample of the tumor using endoscopic ultrasound-guided biopsy. It’s important for the biopsy to include samples from several different areas of the tumor as the characteristics of the SPEN can vary widely across different regions. This ensures the most accurate diagnosis is made.
Treatment Options for Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
When a patient has a specific type of tumor, removing it through surgical enucleation is usually the best treatment. This method tries to preserve as much of the normal tissue, called the parenchyma, as possible. However, sometimes it’s not feasible to remove the tumor surgically, especially if it has grown into or around nearby arteries such as the aorta or superior mesenteric artery.
In these cases, other treatments will be considered. These could include using high-frequency electrical currents to heat and destroy the tumor cells (radiofrequency ablation), using a specialized device to target and kill the tumor cells with radiation (gamma-knife treatment), blocking the blood supply to the tumor to starve it of nutrients (arterial embolization), or using radiation (radiotherapy) or chemotherapy drugs to kill the tumor cells.
About three-quarters of these tumors have receptors for the hormones estrogen and progesterone. It’s thought that a drug called tamoxifen, which interferes with estrogen’s ability to stimulate tumor growth, might be useful when surgery isn’t possible. However, it should be noted that there’s limited evidence for the effectiveness of tamoxifen in these cases, as no major clinical trials have been conducted and the reports of success are only based on individual cases.
What else can Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas be?
When someone is diagnosed with SPENs or Solid-Pseudopapillary Neoplasms of the pancreas, their symptoms can look like a lot of other health problems. So, to make sure it’s SPENs, doctors need to use scans and special tests on tissue samples. They also need to think about other conditions it could be like:
- Mucinous cystic growths in the pancreas
- Islet cell tumors
- Tumors that affect nerve cells and have cyst-like structures (for instance, cystadenoma or cystadenocarcinoma)
- Serous microcystic adenoma
- Intraductal papillary mucinous neoplasm (IPMN), a tumor that grows in the pancreas’ ducts.
What to expect with Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
The overall outlook for individuals diagnosed with SPENs – a type of tumor, is usually positive considering their mild aggressiveness. However, these tumors may become more aggressive in older males. Roughly 10% to 15% of all SPENs tend to become highly malignant, which means they can spread in the body.
Although it has been suggested that factors like the size of the tumor, invasion of lymph vessels or blood vessels, and the Ki-67 index (a measure that helps estimate the growth rate of the tumor) might help predict the severity and the chance of the disease recurrence, more research is needed to validate these predictors.
On a positive note, the overall 5-year survival rate for patients with SPENs is about 97%, implying that 97 out of 100 people are still alive five years after the diagnosis.
Possible Complications When Diagnosed with Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
The major issues after surgery mainly result from the squeezing of nearby body parts, leading to yellowing of the skin and eyes (jaundice) and blockage of the stomach valve, which prevents food and stomach acid from leaving the stomach to enter the small intestine. After the operation, problems can include formation of abnormal connections in the pancreas (pancreatic fistulas), inflammation of the pancreas (pancreatitis), greasy and foul-smelling stools (steatorrhea), infections, bleeding, abnormal connections in the bile ducts (biliary fistulas), and temporary blockage of the intestine (ileus). On top of that, less than 1% of people develop diabetes after surgery. Although it’s uncommon, patients still need regular checks to monitor for any recurrence or spreading of the disease.
Common Post-Surgery complications:
- Jaundice and gastric outlet obstruction
- Pancreatic fistulas
- Pancreatitis
- Steatorrhea
- Infections
- Bleeding
- Biliary fistulas
- Ileus
- Development of diabetes mellitus (<1% of patients)
- Recurrence or metastasis (rare)
Preventing Solid Pseudopapillary Epithelial Neoplasm (SPEN) of the Pancreas
Solid pseudopapillary tumors of the pancreas are rare forms of cancer that can be effectively treated with surgery. Currently, there are no recommended screening procedures to detect these types of tumors earlier. However, if you’re experiencing symptoms such as stomach pain, feeling nauseous, or vomiting, you should seek medical help for a thorough check-up.
