IPLab:Lab 7:Carcinoid

Clinical Summary

This 58-year-old male experienced increasing diarrhea over the 4 months prior to admission. During this period he experienced a weight loss of 40 pounds. Imaging demonstrated a lesion a the ileocecal valve and a laparotomy was performed.

The operative specimen consisted of 12 cm of distal ileum, appendix, cecum and colon. On opening the bowel there was a 4.5 x 3 x 3-cm elliptical submucosal mass at the ileocecal valve that had produced partial obstruction. Several small (2 mm) submucosal masses were found in the cecum nearby. On cut section each lesion was found to be firm, gray-tan and homogeneous involving the muscular wall of the bowel and adjacent mesentery.

Images

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  This is a low-power photomicrograph of the surgical specimen showing basophilic and eosinophilic areas delimiting areas of tumor infiltration.

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  This is a higher-power photomicrograph of the surgical specimen showing the mucosa is normal and the tumor cells are in the submucosa.

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  This is a higher-power photomicrograph of the surgical specimen showing nests of tumor cells (arrows).

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  This is a high-power photomicrograph of the surgical specimen showing the tumor's growth pattern--cells form discrete islands, trabeculae, and glands.

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  This is a high-power photomicrograph of the surgical specimen showing the cellular morphology. The tumor cells are monotonously similar with scant, pink, granular cytoplasm and a round-to-oval stippled nucleus. As in most carcinoid tumors, there is minimal variation in cell and nuclear size, and mitoses are infrequent or absent.

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  This low-power photomicrograph shows how the tumor cells have invaded into the muscularis of the bowel (arrows).

Study Questions

• Where is the most common site for carcinoid tumors of the gastrointestinal tract?

Neuroendocrine cells are normally dispersed along the length of the gastrointestinal tract mucosa as well as in many other organs, such as lung, pancreas, biliary tract, and elsewhere. The appendix is the most common site of gut carcinoid tumors, followed by the small intestine (primarily ileum), rectum, stomach, and colon.

• What is 'carcinoid syndrome' and how common is it?

Carcinoid syndrome occurs in about 1% of all patients with carcinoids and in 20% of those with widespread metastases. Uncertainties remain about the precise origin of the carcinoid syndrome, but most manifestations are thought to arise from excess elaboration of serotonin. The clinical syndrome can include cutaneous flushes and apparent cyanosis; intestinal hypermotility (diarrhea, cramps, nausea, vomiting); asthmatic bronchoconstrictive attacks; hepatomegaly (due to metastases); systemic fibrosis (cardiac, aortic, retroperinoteal. pelvic).

• What is the prognosis for patients with carcinoid tumors?

The overall 5-year survival rate for carcinoid tumors (excluding appendiceal) is approximately 90%. Even with small bowel tumors and hepatic metastases, there is a 50% 5-year survival. Widespread disease, however, usually causes death.

Additional Resources

Reference

• eMedicine Medical Library: Malignant Carcinoid Syndrome
• Merck Manual: Overview of Carcinoid Tumors
• Merck Manual: Carcinoid Syndrome

Journal Articles

• Shebani KO, Souba WW, Finkelstein DM, Stark PC, Elgadi KM, Tanabe KK, Ott MJ. Prognosis and survival in patients with gastrointestinal tract carcinoid tumors. Ann Surg 1999 Jun;229(6):815-21; discussion 822-3.

Images

• PEIR Digital Library: Carcinoid Images
• WebPath: Small Intestine