argentaffinoma /är′jentaf′inō″mə/ pl. argentaffinomas, argentaffinomata, a tumor that secretes large amounts of the hormone serotonin. It usually arises in the GI tract anywhere between the stomach and rectum and can metastasize to the liver. In the liver the tumor produces and releases large quantities of serotonin into the systemic bloodstream, resulting in carcinoid syndrome, which is characterized by flushing, swelling of the face, flat angioma on the skin, diarrhea, bronchial spasm, rapid pulse, low blood pressure, and tricuspid and pulmonary stenosis, often with regurgitation. Treatment is with surgery, radiation therapy, chemotherapy, or biotherapy. Carcinoid tumors are considered a type of endocrine tumor.
