History
43-year-old male who has a history of gastrointestinal stromal tumor diagnosed status postexploratory laparotomy. Evaluation for metastatic diseases is requested.
Findings
There is a single abnormality in the loop of bowel below the umbilicus deep (Figures 11.1.1 and 11.1.2) in the abdomen that is moderately hypermetabolic with wall thick- ening on CT consistent with malignancy. The ground glass density on CT in the right pulmonary apex is mildly active probably representing inflammatory changes. The prominent activity in the right colon is physiologic. The activity near the cervical ver- tebrae posteriorly is consistent with fat mobilization (Figure 11.1.3).
Impression
1. Hypermetabolism in a thickened loop of bowel as described above compatible with known malignancy.
2. Presumed inflammation in right pulmonary apex.
3. No evidence of metastatic disease.
Discussion
Gastrointestinal stromal tumors (GISTs) are a group of rare soft tissue tumors that constitutes 80% of the GI mesenchymal tumors. This represents less than 3% of all GI malignancies. Both men and women are affected between the ages of 40 and 70 years.
Fifty to seventy percent of the GISTs occur in the stomach, 33% in the small bowel, and 5% to 15% in the colorectal.
The typical symptoms include abdominal discomfort (or pain), vomiting, fecal blood, and fatigue secondary to anemia.
CT with contrast can provide information regarding the location of the abnormal growth. It is also very sensitive in detecting any metastatic involvement including the liver, peritoneum, and lungs. MRI is used to evaluate soft tissue mass and lesion vascularity. Ultrasound guided biopsy follow by immunohistochemical staining will provide additional character of the tumor. PET can determine if any other malignancy is involved where CT (MR) might have missed the diagnosis. Special diagnostic kits
11 Gastrointestinal Tumors
Heidi R. Wassef
Case 11.1
120
FIGURE11.1.1.
FIGURE11.1.2. FIGURE11.1.3.
are now commercially available to detect GISTs with CD-117 (and CD-34 antigen) surface tissue expression.
The treatment of GISTs is primarily surgical. Only 10% of patients will remain symptom free after treatment. As a rule of thumb, small GISTs (<1cm in size) rarely metastasize; whereas larger GISTs (>15cm) will inevitably spread.
The overall 1-year survival rate of GISTs is 69%. The 3-year survival rate is 29% to 35% and 5-year is 29% to 35%.
Follow-up
In this case scenario, PET has successfully downstaged the original malignancy sug- gested from CT.
122 Part II Clinical Cases
History
67-year-old male who presented with jaundice. A biliary stent was placed endoscopi- cally and an ulcerative mass noted in the post-bulbar duodenum and confirmed on CT.
The current evaluation is for staging.
Findings
There is thickening of the medial wall of the descending duodenum with accompany- ing intense hypermetabolism (Figures 11.2.1 and Figure 11.2.2), between the duodenal lumen and the stent. The lesion is about 2 cm in diameter and the intense hyper- metabolism is consistent with malignancy. Additionally, there is a focal area of intense hypermetabolism of about 1.5 cm dimension in the posteromedial cortex of the upper right kidney. An apparent cortical lesion appears to be a misregistered prominent
Case 11.2
FIGURE11.2.1.
11 Gastrointestinal Tumors 123
upper pole calyx. There are a few scattered peripheral radiodensities that are inter- preted as minor atelectasis on CT. Incidental notations are made of pneumobilia related to the stent and high-density material in the gallbladder, which is probably con- trast from a previous radiographic exam.
Impression
1. Intense hypermetabolism of the wall thickening of the left/medial aspect of the descending duodenum, between the duodenal lumen and the biliary stent, consis- tent with malignancy.
2. No evidence of regional or distant metastatic disease.
FIGURE11.2.2.
