Tumors that occur in the small intestine include:

• Adenocarcinoma (majority of cases).
• Lymphoma (uncommon), which is usually of the non-Hodgkin type. (Refer to the PDQ summary on Adult Non-Hodgkin Lymphoma Treatment ¹ for more information.)
• Sarcoma (most commonly leiomyosarcoma and more rarely angiosarcoma or liposarcoma).
• Carcinoid. (Refer to the PDQ summary on Gastrointestinal Carcinoid Tumor Treatment ² for more information.)
• Gastrointestinal stromal tumors. (Refer to the PDQ summary on Adult Soft Tissue Sarcoma Treatment ³ for more information.)

The majority of malignant neoplasms of the small intestine are adenocarcinomas (50% or more) and are more commonly located in the duodenum and jejunum than in the ileum.[1] Small intestine carcinomas may occur synchronously or metachronously at multiple sites.

Leiomyosarcomas occur most often in the ileum.

Some 20% of malignant lesions of the small intestine are carcinoid tumors, which occur more frequently in the ileum than in the duodenum or jejunum and may be multiple.

It is uncommon to find malignant lymphoma as a solitary small intestine lesion.

References

1. Small intestine. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 107-112.