A rare neoplastic disease characterized by the occurrence of a hormonal syndrome resulting from secretion of humoral factors (including polypeptides, vasoactive amines, and prostaglandins) from a functional neuroendocrine tumor (particularly from the midgut), typically manifesting with increased bowel movements and diarrhea, episodic vasoactive flushes (particularly of the face), hypotension, tachycardia, venous telangiectasia, dyspnea, and bronchospasms, as well as long-term fibrotic changes in the mesentery, retroperitoneum, and of the cardiac valves. [from
ORDO]