Pancreatic neuroendocrine tumors (PNETs) are a rare type of tumor that arises from the hormone-producing cells of the pancreas. Unlike the more common pancreatic adenocarcinoma, which originates from the exocrine part of the pancreas, PNETs can produce hormones that cause a variety of symptoms. Recognizing the signs of these tumors can be challenging because their symptoms often overlap with other conditions or may be subtle and develop slowly.
**Signs and Symptoms of Pancreatic Neuroendocrine Tumors**
The symptoms of PNETs depend largely on whether the tumor is functioning (hormone-producing) or non-functioning (not producing hormones), as well as the size and location of the tumor.
1. **Symptoms Related to Hormone Overproduction**
Functioning PNETs secrete excess hormones, leading to specific syndromes depending on the hormone involved:
– **Insulinomas:** These tumors produce too much insulin, causing low blood sugar (hypoglycemia). Symptoms include sweating, dizziness, confusion, weakness, shakiness, irritability, and in severe cases, fainting or seizures.
– **Gastrinomas:** These tumors secrete excess gastrin, which stimulates the stomach to produce too much acid. This can cause severe stomach ulcers, abdominal pain, diarrhea, and sometimes bleeding. This condition is known as Zollinger-Ellison syndrome.
– **Glucagonomas:** These produce excess glucagon, leading to mild diabetes symptoms, weight loss, anemia, and a distinctive red, blistering rash that appears and disappears in different areas of the body.
– **Somatostatinomas:** These tumors secrete somatostatin, which inhibits many digestive hormones, causing diabetes, gallstones, diarrhea, and weight loss.
– **VIPomas:** These produce vasoactive intestinal peptide (VIP), leading to watery diarrhea, low potassium levels, and dehydration.
2. **Symptoms Related to Tumor Growth and Location**
Whether functioning or not, as PNETs grow, they can cause symptoms by pressing on nearby structures:
– **Abdominal pain or discomfort:** This is often vague and can be persistent or intermittent.
– **Jaundice:** Yellowing of the skin and eyes may occur if the tumor blocks the bile duct.
– **Weight loss:** Unintentional weight loss is common and may be due to the tumor’s metabolic effects or decreased appetite.
– **Changes in bowel habits:** Diarrhea or constipation can occur, sometimes related to hormone secretion or tumor effects on digestion.
– **Palpitations or rapid heartbeat:** This can be due to hormone effects or general systemic illness.
3. **General Symptoms Common to Many Cancers**
– Fatigue and weakness not relieved by rest.
– Loss of appetite.
– Unexplained fever or frequent infections.
Because PNETs can produce hormones that affect multiple body systems, symptoms can be diverse and sometimes confusing. For example, flushing of the face and neck, wheezing, and diarrhea may be signs of carcinoid syndrome, a condition caused by hormone secretion from some neuroendocrine tumors.
**Why Are These Tumors Difficult to Detect Early?**
PNETs often grow slowly and symptoms may be mild or nonspecific for a long time. Many people do not notice symptoms until the tumor has grown large or spread. Hormonal symptoms may be mistaken for other common conditions such as ulcers, diabetes, or skin disorders. Non-functioning tumors may produce no symptoms until they cause mass effects.
**Additional Signs That May Appear**
– New onset diabetes or worsening control of existing diabetes.
– Skin changes such as redness, flushing, or rashes.
– Digestive disturbances including bloating, indigestion, or fatty stools due to impaired digestion.
– Low blood sugar episodes in insulin-s
