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eMedicine Journal > Pediatrics > Oncology
Carcinoid Tumor

Synonyms, Key Words, and Related Terms: carcinoid tumor, neuroendocrine tumor, primitive stem cells, carcinoid syndrome, foregut carcinoid tumors, midgut carcinoid tumors, hindgut carcinoid tumors, gut wall tumors
Author Information | Introduction | Clinical | Workup | Treatment | Follow-up | Test Questions | Bibliography

AUTHOR INFORMATION Section 1 of 8    Click here to go to the top of this page Click here to go to the next section in this topic

Authored by Cameron K Tebbi, MD, Medical Director, Department of Pediatric Hematology-Oncology, Tampa Children's Hospital

Cameron K Tebbi, MD, is a member of the following medical societies: American Society of Clinical Oncology, American Society of Pediatric Hematology/Oncology, Children's Oncology Group, Florida Association of Pediatric Tumor Programs, Histiocyte Society, International Society of Paediatric Oncology, and International Union Against Cancer

Edited by Kathleen Sakamoto, MD, Professor, Department of Pediatrics, Division of Hematology-Oncology and Pathology and Laboratory Medicine, Mattel Children's Hospital, David Geffen School of Medicine, University of California at Los Angeles; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Timothy P Cripe, MD, PhD, Associate Professor of Pediatric Hematology/Oncology, University of Cincinnati; Director, Translational Research Trials Office, Department of Pediatrics, Cincinnati Children's Hospital Medical Center; Samuel Gross, MD, Professor Emeritus, Department of Pediatrics, University of Florida, Clinical Professor, Department of Pediatrics, UNC, Adjunct Professor, Department of Pediatrics, Duke University; and Max J Coppes, MD, PhD, MBA, Executive Director, Center for Cancer and Blood Disorders, Children's National Medical Center

Author's Email:Cameron K Tebbi, MDClick here to view conflict-of-interest information on the author of this topic
Editor's Email:Kathleen Sakamoto, MD 

eMedicine Journal, March 3 2007, VOLUME 8, Number 3
INTRODUCTION Section 2 of 8   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Background:

Origin and general involvement and presentation

Carcinoid tumors are derived from primitive stem cells in the gut wall but can be seen in other organs (Broaddus, 2003), including the lungs (Moraes, 2003), mediastinum, thymus (Soga, 1999) liver, pancreas, bronchus, and ovaries (Piura, 1995). In children, most cases occur in the appendix, and most are benign and asymptomatic.

Although rare, aggressive and metastatic disease (eg, to the brain [Hlatky, 2004] do occur. Even tumors in the appendix can metastasize (Volpe, 2000). Depending on size and location, carcinoid tumors can cause various symptoms, including carcinoid syndrome. Carcinoid tumors of the ileum and jejunum, especially those larger than 1 cm, are most prone to produce this syndrome, at least in adults.

Classification

Carcinoid tumors generally are classified on the basis of the location in the primitive gut (ie, foregut, midgut, hindgut) that gives rise to the tumor.

Foregut carcinoid tumors are divided into sporadic primary tumors and those secondary to achlorhydria. Sporadic primary foregut tumor encompasses carcinoids of the bronchus, stomach, proximal duodenum, and pancreas.

Midgut tumors are derived from the second portion of the duodenum, the jejunum, the ileum, and the right colon. These account for 60-80% of all carcinoid tumors in adults and are also seen in children (Schmittenbecher, 2001), especially those of the appendix and distal ileum. Appendicular carcinoid tumors are most common (Bethel, 1997; Pelizzo, 2001). In children, more than 70% of these tumors occur at the tip of the appendix, and they are often an incidental finding in appendectomy specimens. In one study, carcinoid tumors were found in 0.169% of 4747 appendectomies (Doede, 2000). Bulky tumors are relatively rare and require somewhat extensive cecectomy or, when tumor infiltration is beyond the cecum, ileocecal resection (Soreide, 2000; D’Aleo, 2001; Pelizzo, 2001).

Hindgut carcinoid tumors include those of the transverse colon, descending colon, and rectum.

Carcinoid tumors also can arise from the Meckel diverticulum, cystic duplications, and the mesentery. Each of these entities has distinctive clinical, histochemical, and secretory features. For example, foregut carcinoids are argentaffin negative and have low serotonin content, but they secrete 5-hydroxytryptophan (5-HTP), histamine, and several polypeptide hormones. These tumors can metastasize to bone, and they may be associated with atypical carcinoid syndrome, acromegaly, Cushing disease, other endocrine disorders, telangiectasia, or hypertrophy of the skin in the face and upper neck.

Midgut carcinoids are argentaffin positive and can produce high levels of serotonin 5-hydroxytryptamine (5-HT), kinins, prostaglandins, substance P (SP), and other vasoactive peptides. These tumors have a rare potential to produce corticotropic hormone (previously adrenocorticotropic hormone, ACTH). Bone metastasis is uncommon.

Hindgut carcinoids are argentaffin negative and rarely secrete 5-HT, 5-HTP or any other vasoactive peptides. Therefore, they do not produce related symptomatology. Bone metastases are not uncommon in these tumors.

Pathophysiology: Carcinoid tumors are of neuroendocrine origin and derived from primitive stem cells, which can give rise to multiple cell lineages. In the intestinal tract, these tumors develop deep in the mucosa, growing slowly and extending into the underlying submucosa and mucosal surface. This results in the formation of small firm nodules, which bulge into the intestinal lumen. These tumors have a yellow, tan, or gray-brown appearance that can be observed through the intact mucosa. The yellow color is a result of cholesterol and lipid accumulation within the tumor. Tumors can have a polypoid appearance and occasionally become ulcerated. With expansion and infiltration through the submucosa into the muscularis propria and serosa, carcinoid tumors can involve the mesentery. Metastases to the mesenteric lymph node and liver, ovaries, peritoneum, and spleen can occur.

On histologic examination, carcinoid tumors have 5 distinctive patterns: (1) solid, nodular, and insular cords; (2) trabecular or ribbons with anastomosing features; (3) tubules and glands or rosettelike patterns; (4) poorly differentiated or atypical patterns; and (5) mixed patterns. A combination of these patterns is often observed. Tubules can contain mucinous secretions, and individual tumor cells can contain mucin-positive material, which includes the various acidic and neutral intestinal mucin. Rarely do tumors have eosinophilic stroma. Capillaries are often prominent. Cells are uniformly round or polygonal with a central nucleus and punctate chromatin, as well as small nucleoli and infrequent mitosis. The cytoplasm can be slightly acidophilic, basophilic, or amphophilic. Eosinophilic granules may be present.

In midgut carcinoids, cells are arranged in closely packed, round, regular, monomorphous masses. In the appendix, carcinoids appear as discrete yellow nodules in the lumen. Lesions associated with diffuse wall thickening are relatively uncommon. Carcinoid tumors commonly affect the tip of the appendix. Most carcinoid tumors invade the wall of the appendix, and lymphatic involvement is nearly universal. About 75% of patients have evidence of peritoneal involvement. However, only a few patients have regional or distant dissemination. The size of the tumor can be correlated with outcome of the disease in that tumors smaller than 1.5 cm in diameter (after formalin fixation) rarely result in distant metastases or recurrences.

Carcinoid tumors can be associated with concentric and elastic vascular sclerosis resulting in obliteration of vascular lumina and ischemia. A common finding is elastosis and fibrosis that surround nests of the tumor cells and that result in matting of the involved tissues and lymph nodes. Fibroblastic proliferation may result from the stimulation of fibroblast cells by growth factor. This stimulation may be a result of a local release of tumor growth factor (TGF)-beta, beta–fibroblast growth factor (beta-FGF), and platelet-derived growth factor.

Other products of carcinoid tumors include the following:

Classic carcinoid tumor cells are argentaffinic and argyrophilic. At present, immunostain and hormonal markers are used for diagnosis.

Carcinoids may have somatostatin receptors. Five identified somatostatin receptors are members of the G-protein receptor family. Five distinct genes on chromosomes 11, 14, 16, 17, and 20 encode somatostatin receptors. Somatostatin receptors are used to advantage for diagnosing and treating this disease.

Frequency:

CLINICAL Section 3 of 8   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

History: Signs and symptoms of carcinoid tumors vary greatly and depend on the location and size of the tumor and on the presence of metastases. Findings range from no tumor-related findings to full symptoms of carcinoid syndrome. Because carcinoid tumors are rare in children, clinicians rely on reports of adult patients to understand the full scope of the manifestations of the disease.

Causes: The etiology of carcinoid tumors is not known, but genetic abnormalities are suspected. Reported chromosomal abnormalities include changes in chromosomes, such as loss of heterogeneity, and numerical imbalances.

WORKUP Section 4 of 8   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Lab Studies:

Imaging Studies:

Procedures:

Histologic Findings: Please see Pathophysiology above.

TREATMENT Section 5 of 8   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Medical Care: If metastasie occurs and surgical excision is not suitable, consider treatment with currently recommended chemotherapy.

Surgical Care: The treatment of choice is surgical excision, if feasible. The surgical technique may vary according to the type or location of the tumor.

FOLLOW-UP Section 6 of 8   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

Complications:

Prognosis:

TEST QUESTIONS Section 7 of 8   Click here to go to the next section in this topic Click here to go to the top of this page Click here to go to the next section in this topic

CME Question 1: Which one of the following is not a substance that carcinoid tumors produce?


A: 5-hydroxyindoleacetic acid (5-HIAA)
B: 5-hydroxytryptamine (5-HT)
C: Vasoactive intestinal peptide (VIP)
D: Delta–amino levulinic acid (delta-ALA)
E: Histamines

The correct answer is D: Many carcinoid tumors produce 5-HIAA, 5-HT, VIP, and histamines. In fact, levels of these substances can be measured as markers to diagnose the tumor, and they are responsible for the symptoms of carcinoid syndrome.

CME Question 2: Which chromosomal change is reported in carcinoid tumors?


A: 11(11p13) deletion
B: 12(12p14) deletion
C: t(9;22)
D: t(14:18)(q21;q32)
E: t(12;22)

The correct answer is A: MEN 1 gene for multiple endocrine neoplasia type 1 (MEN 1) is located in chromosomal band 11p13 and is likely to function as a tumor-suppressor gene. In 1 study of 46 sporadically occurring tumors, 78% had a loss of heterozygosity (LOH) at this site.

Pearl Question 1 (T/F): Most carcinoid tumors in the pediatric age group are located in the tip of the appendix and are asymptomatic.

The correct answer is True: Carcinoid tumors occur most often in the appendix and are incidentally found during appendectomy.

Pearl Question 2 (T/F): Measurement of urinary isovaleric acid levels is the most reliable test for detecting carcinoid tumors in children.

The correct answer is False: Isovaleric acid is not one of the metabolites found in carcinoid tumors.

Pearl Question 3 (T/F): Cutaneous flushing, diarrhea, wheezing, and symptoms of valvular heart lesions can be signs of a carcinoid tumor.

The correct answer is True: Cutaneous flushing, asthma-like syndrome, diarrhea, abdominal pain, and cardiac symptoms are due to substances carcinoid tumors produce and are a part of carcinoid syndrome.

Pearl Question 4 (T/F): Carcinoid tumor has occurred in association with multiple endocrine neoplasia type 1 (MEN 1) or Peutz-Jegher syndrome.

The correct answer is True: Several reports describe carcinoid tumors occurring in association with MEN 1 and/or Peutz-Jeghers syndrome. The reason for these associations is not known.
BIBLIOGRAPHY Section 8 of 8   Click here to go to the next section in this topic Click here to go to the top of this page

NOTE:
Medicine is a constantly changing science and not all therapies are clearly established. New research changes drug and treatment therapies daily. The authors, editors, and publisher of this journal have used their best efforts to provide information that is up-to-date and accurate and is generally accepted within medical standards at the time of publication. However, as medical science is constantly changing and human error is always possible, the authors, editors, and publisher or any other party involved with the publication of this article do not warrant the information in this article is accurate or complete, nor are they responsible for omissions or errors in the article or for the results of using this information. The reader should confirm the information in this article from other sources prior to use. In particular, all drug doses, indications, and contraindications should be confirmed in the package insert. FULL DISCLAIMER
eMedicine Journal, March 3 2007, VOLUME 8, Number 3
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eMedicine Journals > Pediatrics > Oncology > Carcinoid Tumor
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