eMedicine Specialties > Gastroenterology > Intestine

Intestinal Leiomyosarcoma

Author: Richard K Spence, MD, Senior Vice President for Clinical Affairs, Infonale
Coauthor(s): George Brasinikas, MD, Staff Physician, Department of Pathology, Birmingham Baptist Medical Center
Contributor Information and Disclosures

Updated: Nov 9, 2006

Introduction

Background

Intestinal leiomyosarcomas are mesenchymal tumors of smooth muscle origin. In the past, gastrointestinal stromal tumors (GISTs) were misdiagnosed as leiomyosarcomas. GISTs, however, have recently been shown to lack characteristics of smooth muscle tumors on histologic examination. They are often CD34 immunoreactive and express tyrosine kinase c-kit (CD117) receptor activity, in contrast to leiomyosarcomas. Mutations in the c-kit receptor are linked to neoplastic development.

Approximately 1-2% of solid tumors are soft tissue sarcomas, and leiomyosarcomas comprise roughly 2-9% of these sarcomas. Of leiomyosarcomas, 20% are found in the GI tract, with sites of occurrence evenly divided between the stomach and the small intestine.

Pathophysiology

When considering all primary malignancies of the small bowel, adenocarcinomas tend to occur more proximally, whereas carcinoids, lymphomas, and leiomyosarcomas occur more distally. Depending on the study reviewed, the primary sites of occurrence of leiomyosarcomas are divided equally between the stomach and the small intestine. As many as 50% of the leiomyosarcomas occurring in the small intestine are found in the ileum. Relatively few leiomyosarcomas have been found in the esophagus, colon, or rectum.

The natural history of this tumor involves local growth initially, with much of its growth being extraluminal; thus, obstruction occurs late. Multiple primary sites are unusual. Often, as the size of the leiomyosarcoma increases, necrosis and bleeding follow. This leads to the most common presenting feature in symptomatic patients, bleeding, which often is massive.

Metastasis is primarily hematologic. Lymph node metastasis is rare, occurring in 0-15% of cases, depending on the series. Leiomyosarcomas spread to the liver and peritoneum first. Spread to the lung occurs less frequently than spread to the liver and peritoneum. This is in contrast to other soft tissue sarcomas in which the lung is the most common site of metastasis. About 20-40% of patients have metastasis at the initial laparotomy.

The 2 factors that are recurrent themes in any discussion of leiomyosarcomas are size and grade. These features largely determine the survivability of a patient with this disease. The impact of size is debatable. Logically, resection, which is the only hope for a cure, appears to be more difficult with larger tumors.

If a tumor is larger, metastasis is more likely to have occurred. Because these tumors are extraluminal, they can grow quite large before they become symptomatic. They can range from 4-5 cm in diameter to as large as 19 cm.

The grade of malignancy is judged microscopically and is accepted universally as a prognostic indicator. Generally, high-grade change is considered greater than 5 mitotic figures per 10 high-powered fields.

Recurrence occurs in the peritoneum and/or retroperitoneum. As many as 55% of patients with recurrence have metastatic lesions to the liver at the time that their recurrence is discovered. If a low-grade tumor recurs, it often does so with a new, more aggressive grade of histology.

Frequency

United States

Intestinal leiomyosarcomas are fairly rare, with a frequency of around 1.4 cases per 100,000 patients.

The Martin series, which was composed of 11,438 cases of GI tract tumors from 1944-1982, included only 280 patients with primary small intestine tumors. If ampullar lesions are excluded from this count, 217 cases of primary small intestine tumors, or 2.4%, were in the series.

In 1994, Disario reviewed the cases entered from 1966-1990 in the Utah Cancer Registry; only 328 cases of small intestine cancer were recorded. Of these cases, 41% were carcinoid, 24% were adenocarcinomas, and 11% were sarcomas (1% was not clearly identified).

Carcinoid and adenocarcinomas are far more common, even with ampullar lesions excluded.

A 2004 study by Jun Zhan and colleagues determined that malignant tumors were the most common small intestinal disease. Of 125 patients with malignant tumors, 11% had leiomyosarcoma, 11% had adenocarcinoma, and 9% had small intestinal lymphoma. Patients with primary small intestinal disease most commonly presented with periumbilical pain.

International

Information on international frequency is unavailable.

Mortality/Morbidity

The prognosis ranges from universally fatal to poor. Size and grade are determinants of prognosis, depending on the series. Histology consisting of high-grade malignancy and a large size portends a poor prognosis. Size affects resectability.

• With curative resection, the 5-year survival rate of patients with a gastric leiomyosarcoma is 68-90%, whereas small intestine tumors are associated with a survival rate of 40-50%. Distant metastasis decreases the survival rate to around 30%.
• Evans (1985) presented a 10-year series in which he followed the cases of 56 patients. Roughly 70% of these had high-grade tumors. Patients with high-grade tumors had a median survival of 25 months. Patients with a low-grade tumor survived much longer, with a median survival of 98 months. In fact, 2 patients (15%) survived the study. Overall, the 5-year survival rate runs from 18-50%. This range largely is a factor of patient selection.
• In a study published in 1998, all leiomyosarcomas occurring over the span of 45 years at Charity Hospital in New Orleans were reviewed (Hill MA, 1998). The authors found that leiomyosarcomas of the small intestine and uterus had a somewhat better prognosis than those occurring in the retroperitoneum.

Sex

Depending on the study, the male-to-female ratio ranges from 1:1 to 2:1. No study was found in which sex was a prognostic indicator.

Age

Leiomyosarcomas primarily are a disease of middle-aged persons, with the average age on presentation falling between the fifth and seventh decades of life.

Clinical

History

Symptoms are usually lacking; if present, they are nonspecific. Vague complaints, such as malaise, fatigue, and nonfocal abdominal pain, are often described.

• The sign most often cited is bleeding. These tumors sometimes necrose and bleed into the bowel.
  • In one study, 59% of patients with leiomyosarcomas were symptomatic. For 70% of these patients, bleeding was the primary symptom. Of those who bled, 69% bled acutely, and 82% of the acute bleeders required transfusions. Of those who bled acutely, 45% required emergent laparotomy. Duodenal tumors bled most often. Of the duodenal tumors, 75% bled and were hemorrhagic in nature, requiring an average replacement of 11.5 units of blood.
  • Complaints of malaise and fatigue likely are due to anemia, which often is present in patients who bleed chronically.
• Weight loss is reported as a late feature, with an incidence around 20%.
• Past medical history: One study performed by Hill in 1986 reported a possible relationship between leiomyosarcomas and Crohn disease. In this series, which reviewed more than 11,000 cases, 6% of the patients with leiomyosarcomas also had a history of Crohn disease.

Physical

• Unless the patient is bleeding or is acutely obstructed, physical findings usually are absent.
• A mass rarely is palpable.

Causes

Causes of leiomyosarcoma are unknown.

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