Peripheral primitive neuroectodermal tumors (pPNETs) are small embryonic carcinomas that develop in the soft tissue and bone, away from the central nervous system (CNS) and sympathetic nervous system (SNS).
A primitive neuroectodermal tumor (PNET) is a former name for a group of rare, aggressive tumors consisting of embryonic tissue.
The tumors that doctors used to group under PNETs are primitive or embryonic cells that began to develop in an erratic way when the person was still an embryo, before they were born.
If a doctor finds a PNET in the brain or CNS, they categorize this as a central PNET (cPNET).
However, these tumors can also develop outside the CNS in the chest wall, around the vertebrae of the spine, in the pelvis, and in the limbs. Doctors refer to these as peripheral PNETs (pPNETs).
Read on to learn more about the symptoms and causes of pPNETs, diagnosis, treatment options, and more.
pPNETs cause different symptoms depending on where they develop. Most often, they develop in the area around the chest and lungs, the abdomen, and pelvis, according to a 2023 case study. Only around 6% of pPNETs occur outside the bones.
The symptoms of pPNETs in the most common areas may include:
- abdominal pain or swelling
- fluid buildup in the abdomen, known as ascites
- mass effect, which refers to the effects of the tumor pushing against nearby tissue
The direct cause of PNETS and pPNETs is
Genetic changes can change how cells work, divide, and end their life cycles, which can result in cancer. Cancer increases the speed at which cells grow and divide. Some pPNETs might relate to these genetic changes.
PNETs develop from the external layer of cells surrounding a developing embryo, known as the ectoderm. The classification system for PNETs was updated in 2016, and new diagnostic techniques are helping doctors classify different tumors.
A doctor may detect a pPNET on an MRI. During the imaging test, pPNETs
In a 2019 series of 89 case studies, the mean size of pPNET tumors was 5.07 inches (12.9 centimeters).
A surgeon may then remove a pPNET and send it for a biopsy. During the biopsy, a neuropathologist (a doctor specializing in diagnosing CNS diseases) examines the tissue under a microscope. pPNETs have certain features that identify them, including:
- rosettes, or multiple cells that group together around a single cell in the shape of a rose
- a genetic marker called CD99, which is present in 90% to 100% of pPNET cases
- the presence of at least two proteins that suggest the involvement of neural cells, known as neural markers
Cancers receive a grade ranging from 0 to 4, which shows how aggressive or able they are to invade nearby tissue. All PNETs are grade 4 cancers, meaning they are aggressive and spread rapidly.
Where possible, the
Other treatments for pPNETs include chemotherapy and radiation therapy. A person may need chemotherapy or radiation therapy after surgical removal.
pPNETs are aggressive and spread quickly. A 2019 case study series found that the median overall survival for people with a pPNET diagnosis was 15 months.
However, different factors can affect a person’s outlook, including:
- the grade of the tumor
- where the tumor has grown
- what type of tumor it is
- how far the tumor has spread
- the results of genetic testing
- the individual’s age
- how much of the tumor surgeons can remove
A person’s doctor can provide more accurate information about their outlook based on their circumstances.
Peripheral neuroectodermal tumors (pPNETs) are rare, aggressive tumors. They can develop in the bone and soft tissue, often affecting the chest, lung, abdomen, or pelvic area.
pPNETS can cause abdominal pain and swelling, fluid buildup, and other symptoms that depend on where the tumor has developed.
A surgeon can send the tumor tissue for a biopsy to diagnose a pPNET after removal. People may also receive radiation therapy or chemotherapy after or instead of surgical removal.