Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Related to carcinoid: carcinoid syndrome, Carcinoid tumor


1. a yellow circumscribed tumor of the gastrointestinal tract or bronchus formed from chromaffin cells. See also carcinoid syndrome.
carcinoid syndrome a symptom complex associated with carcinoid tumors (argentaffinomas), marked by attacks of severe cyanotic flushing of the skin lasting from minutes to days and by watery diarrhea, bronchoconstrictive attacks, sudden drops in blood pressure, edema, and ascites. Symptoms are caused by serotonin, prostaglandins, and other biologically active substances secreted by the tumor.

The specific symptoms associated with this disorder depend upon the site of the primary tumor; tumors are found most commonly in the appendix and the terminal third of the ileum but can also be in the bronchi, ovaries, testes, and anywhere along the entire length of the alimentary tract. The full set of carcinoid symptoms are manifested only when the liver is involved.

Diagnosis of the condition is established by a 24-hour urine test for 5-hydroxyindoleacetic acid (5-HIAA), the end product of the breakdown of tryptophan to serotonin. Patients with carcinoid syndrome may have very high levels of 5-HIAA, 100 to 500 mg in 24 hours.

Carcinoid tumors are not always benign and should be approached as if they were malignant growths. Surgical excision of the tumor and any associated mesenteric nodes is the treatment of choice. Chemotherapy can be used with metastatic disease, and other drugs are prescribed as indicated to manage the hypotension, diarrhea, flushing, and other symptoms. Efforts are made to improve nutrition and to avoid serotonin-containing foods, such as walnuts and bananas, which are known to precipitate an attack and make accurate diagnosis difficult.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

car·ci·noid tu·mor

a usually small, slow-growing neoplasm composed of islands of rounded, oxyphilic, or spindle-shaped cells of medium size, with moderately small vesicular nuclei, and covered by intact mucosa with a yellow cut surface; neoplastic cells are frequently palisaded at the periphery of the small groups, and the latter have a tendency to infiltrate surrounding tissue. Such neoplasms occur anywhere in the gastrointestinal tract (and in the lungs and other sites), with approximately 90% in the appendix and the remainder chiefly in the ileum, but also in the stomach, other parts of the small intestine, the colon, and the rectum; those of the appendix and small tumors seldom metastasize, but reported incidences of metastases from other primary sites and from tumors exceeding 2.0 cm in diameter vary from 25-75%; lymph nodes in the abdomen and the liver may be conspicuously involved, but metastases above the diaphragm are rare. About 1% of cases are associated with the carcinoid syndrome, usually after the portal circulation is bypassed as in cases involving liver metastases.
See also: carcinoid syndrome.
Farlex Partner Medical Dictionary © Farlex 2012


A small, slow-growing, benign or malignant tumor, found usually in the gastrointestinal tract, that is composed of islands of rounded cells and secretes serotonin.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A well-differentiated tumour of neuroendocrine-neural crest origin, which has paracrine activity. 85% of carcinoid tumours are located in the GI tract (appendix, liver, ileum, stomach, colon, rectum),10% in the lungs and bronchi, and the rest in the breast, kidney, ovary, prostate, skin, thymus, and elsewhere.

Clinical findings
Flushing, tachycardia, facial and periorobital swelling, low blood pressure, abdominal pain, weight loss, diarrhoea.
Appendiceal carcinoids are clinically benign; liver carcinoids are usually functionally malignant, as they release large amounts of vasoactive amines (e.g., serotonin) into the circulation.

Increased serotonin, 5-HIAA in serum, urine.

Carcinoids basic classification
Microcarcinoid Tumourlet < 0.5 cm in diameter.
Carcinoid Benign Usually measure > 0.5 cm; either invades muscularis mucosae or is macroscopically visible, but confined to mucosa or submucosa and not angioinvasive.
Borderline carcinoid Either angioinvasive, but measures < 1 cm and is confined to mucosa/submucosa or 1–2 cm, no angioinvasion and limited to the mucosa/submucosa.
Mucinous/goblet cell carcinoid Aggressive; possibly same as agyrophilic adenocarcinoma.
Atypical carcinoid Carcinoid + necrosis OR mitoses > 2/10hpf OR cytological atypia.
Malignant carcinoid Carcinoid + functional tumour OR > 1 cm + angioinvasion OR invades muscularis propria.

Note: The term neuroendocrine tumour is increasingly preferred.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

Patient discussion about carcinoid

Q. what is carcinoid tumors? I had my appendix removed and the doctor came in the room very shocked and said it was full of carcinoid tumors. Im scared to get them somewhere else.

A. ya I have pain all the time but the doctors wont give me anything cuz im so young they don't want me hooked on anything. thank you sooo much for being so kind.

More discussions about carcinoid
This content is provided by iMedix and is subject to iMedix Terms. The Questions and Answers are not endorsed or recommended and are made available by patients, not doctors.
References in periodicals archive ?
However, for large carcinoids, adenocarcinomas, or lymphomas, for example, more extensive surgery and/or chemotherapy are required.
The surgical specimen from mRPLND did not include teratomatous component and showed the same histology as previous primary testicular carcinoid tumour (Fig.
Furthermore, appendix is the second most common location for midgut carcinoids as it helps to spread cancer to the entire liver.
In this study, we diagnosed incidental neoplastic lesions like carcinoid tumour, and hence, routine histopathological examination of the appendicectomy specimen is essential.
Carcinoid tumors are estimated to occur in 1.9 individuals per 100,000 annually.
Goblet cell carcinoid tumors manifest more aggressive behavior than other carcinoid tumors.
Neuroendocrine tumors of the lung include carcinoid tumors, small cell carcinomas, and LCNECs.
Carcinoid crisis is a severe case of flushing, low blood pressure, difficulty breathing and an irregular heartbeat.
Normally, 1% of dietary tryptophan is converted to serotonin, but in carcinoid, 70% of it is converted to serotonin, which in turn is converted to 5-hydroxyindoleacetic acid (5-HIAA) in the liver and secreted in urine.
(3) Occasionally, idiopathic cecal ulcers may be accompanied by incidental appendiceal carcinoids. In a case report from Ince et al.
He covers essentials of medical, surgical, and radiation oncology; interventional radiology in the treatment of cancer patients; chemotherapeutic agents; colorectal cancer; cancer of the pancreas; carcinoid tumor (neuroendocrine tumors of the gastrointestinal tract); hepatocellular carcinoma; cholangiocarcinoma; lung cancer (non-small cell); head and neck cancer; renal cell carcinoma; urothelial cancer and transitional cell cancer; prostate cancer; breast cancer; gynecologic tumors; clinical trials and interventional oncology; and building an interventional oncology practice.