Case 3
History:
54 year old male with chronic abdominal pain and weight loss
Findings:
Enhanced abdominal CT showing a lobulated mildly enhancing soft tissue lesion adjacent to the small bowel loops. It was somewhat difficult to determine whether the lesion arose from a small bowel loop or was merely abutting it.
Diagnosis:
Gastrointestinal stromal tumors (GIST)
Discussion:
GIST tumors are rare and account for 0.1 to 3 percent of all gastrointestinal (GI) cancers and 5.7 percent of sarcomas. These tumors are defined as spindle cell, epithelioid, or pleomorphic mesenchymal tumors of the GI tract,. 70 to 80 percent of the lesions are benign.
GIST tumors can be depicted anywhere in the GI tract or in the mesentery/omentum. They originate in the bowel wall. The most common location of GIST tumors is in the stomach and small bowel. Multiple tumors are extremely unusual. In 10 percent of cases, tumors are seen outside the bowel. Small bowel GIST is more aggressive and carries a poor prognosis.
A heterogeneous group of gastrointestinal smooth muscle tumors has been recognized for many years. These tumors are now grouped under the umbrella title of gastrointestinal stromal tumours (GISTs), of which 70- 80 percent are the benign form leiomyomata. Some malignant lesions, composed primarily of spindle shaped cells, comprise leiomyosarcomas, whereas those comprised primarily of epithelioid cells are designated leiomyoblastomas.
CT therefore provides the basis for diagnosis and staging in most patients. Tumors are usually of varying density and show patchy enhancement. The diagnosis of GIST is seldom considered initially. They may mimic more common tumors such as pancreatic cancer or lymphoma. Many GISTs achieve enormous size before diagnosis and demonstrate considerable cystic/necrotic change.
