Symptoms can be caused by the growth of the tumor and/or by hormones the tumor makes. Some tumors may not cause symptoms. Conditions other than islet cell tumors can cause the symptoms listed below. A doctor should be consulted if any of these problems occur.

Signs and symptoms of a non-functioning islet cell tumor

A non-functioning islet cell tumor may grow for a long time without causing symptoms. It may grow large or spread to other parts of the body before it causes symptoms, such as:

  * Diarrhea.
  * Indigestion.
  * A lump in the abdomen.
  * Pain in the abdomen or back.
  * Yellowing of the skin and whites of the eyes.

A tumor that makes pancreatic peptides (PPoma) often has no symptoms.

Signs and symptoms of a functioning islet cell tumor

The symptoms of a functioning islet tumor depend on the type of hormone being made.

Too much gastrin may cause:

  * Stomach ulcers that keep coming back.
  * Pain in the abdomen, which may spread to the back. The pain may come and go and it may go away after taking an antacid.
  * The flow of stomach contents back into the esophagus (gastroesophageal reflux).
  * Diarrhea.

Too much insulin may cause:

  * Low blood sugar. This can cause blurred vision, headache, and feeling lightheaded, tired, weak, shaky, nervous, irritable, sweaty, confused, or hungry.
  * Feeling a fast heartbeat.

Too much glucagon may cause:

  * Skin rash on the face, stomach, or legs.
  * High blood sugar. This can cause headaches, frequent urination, dry skin and mouth, or feeling hungry, thirsty, tired, or weak.
  * Blood clots in the lung. This can cause shortness of breath, cough or pain in the chest. Blood clots in the arm or leg can cause pain, swelling, warmth, or redness of the arm or leg.
  * Diarrhea.
  * Weight loss for no known reason.
  * Sore tongue or sores at the corners of the mouth.

Too much vasoactive intestinal peptide (VIP) may cause:

  * Very large amounts of watery diarrhea.
  * Dehydration. This can cause feeling thirsty, making less urine, dry skin and mouth, feeling tired, headache, or dizziness.
  * Low potassium level in the blood. This can cause muscle weakness, aching, or cramps, numbness and tingling, frequent urination, and feeling a fast heartbeat, confused, or thirsty.
  * Cramps or pain in the abdomen.
  * Weight loss for no known reason.

Too much somatostatin may cause:

  * High blood sugar. This can cause headaches, frequent urination, dry skin and mouth, or feeling hungry, thirsty, tired, or weak.
  * Diarrhea.
  * Steatorrhea (very foul-smelling stool that floats).
  * Gallstones.
  * Yellowing of the skin and whites of the eyes.
  * Weight loss for no known reason.

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National Cancer Institute