[Diagnostic imaging of gastrointestinal leiomyosarcoma. Experience with 12 cases]

Gastrointestinal (GI) leiomyosarcoma is an uncommon malignant cancer arising in the smooth muscle of the alimentary tract. It is known for its widely variable patterns and aspecific symptoms and signs preventing correct clinical assessment in the majority of cases. We will illustrate the key role of diagnostic imaging in the detection and staging of this lesion, describing the most suggestive imaging findings for the correct diagnosis.

January, 1990, to June, 1998, we examined 12 patients with GI leiomyosarcoma; they were 10 men and 2 women whose age ranged 42 to 85 years (mean: 63.7 years). Four lesions were found in the stomach, 3 in the jejunum and ileum, and 2 in the rectum. Due to the difficult clinical assessment of this type of lesion and to the development of emergency conditions, we could plan no diagnostic protocol in advance; thus, the most suitable diagnostic imaging approach was decided on the spot for studying the supposedly involved GI portions. Double contrast studies, US, CT and endoscopy were performed and each patient underwent at least two examinations.

Barium contrast studies were performed in 9 patients: the lesion was detected in 7 cases and tumor site and extent were defined in 5, while the double contrast study of the colon allowed to exclude large bowel involvement in 2 ileal tumors. In all 9 cases US and US-guided endoscopy permitted better assessment of extra-luminal spread and involvement of adjacent organs. CT, which is essential to staging, provided useful information suggesting the lesion nature: a round, inhomogeneous mass in continuity with the intestinal wall, with irregular margins, peripheral enhancement after i.v. injection of contrast material and a central necrotic area. Histology confirmed CT diagnosis in 7/9 cases while an aspecific diagnosis of large retroperitoneal and abdominal lesion was made in 2 cases. CT did not allow to define the origin of 2 large exophytic lesions in the stomach and jejunum and missed peritoneal metastases in 3 cases.

Although the aspecific and quite variable clinical patterns make it extremely difficult to plan a correct diagnostic protocol, in our experience all diagnostic imaging techniques played a fundamental role in identifying and staging alimentary tract leiomyosarcoma. Particularly, CT showed high sensitivity and specificity in characterizing and staging this lesion but exhibited rather poor sensitivity in recognizing peritoneal spread.