Some carcinoid tumors don't cause any signs or symptoms. When they do occur, signs and symptoms are usually vague and depend on the location of the tumor. Carcinoid tumors in the lungs Signs and symptoms of carcinoid lung tumors include: 
Chest pain
Wheezing
Shortness of breath
Diarrhea
Redness or a feeling of warmth in your face and neck (skin flushing)
Weight gain, particularly around the midsection and upper back
Pink or purple marks on the skin that look like stretch marks
 Carcinoid tumors in the digestive tract Signs and symptoms of carcinoid tumors in the digestive tract include: 
Abdominal pain
Diarrhea
Nausea, vomiting and inability to pass stool due to intestinal blockage (bowel obstruction)
Rectal bleeding
Rectal pain
Redness or a feeling of warmth in your face and neck (skin flushing)
