Any information contained in this pdf file is automatically generated from digital ..... Rumack CM, Wilson SR, Charboneau, JW, Levine D. Diagnostic Ultrasound,.
Imaging findings of gastrointestinal stromal tumours (GISTs) Poster No.:
C-0667
Congress:
ECR 2014
Type:
Educational Exhibit
Authors:
J. Praia , C. Maciel , J. Albuquerque , R. Cunha , J. Costa ;
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Barreiro/PT, Porto/PT
Keywords:
Neoplasia, Diagnostic procedure, Contrast agent-oral, Contrast agent-intravenous, Ultrasound, MR, CT, Stomach (incl. Esophagus), Gastrointestinal tract, Abdomen
DOI:
10.1594/ecr2014/C-0667
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Learning objectives •
Brief overview of the epidemiological, macroscopical, histological, cytological and clinical characteristics of Gastrointestinal Stromal Tumours (GISTs).
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To illustrate and describe imaging findings that suggest the diagnosis of GISTs.
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Description of the different imaging modalities available for the study of GISTs and the spectrum of imagiological features of this entity on each of them.
Background •
Gastrointestinal stromal tumors (GISTs) account for approximately 80% of GI mesenchymal tumors but are nevertheless rare tumors, constituting less than 3% of all GI malignant neoplasm.
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Previously, these tumors were classified as GI leiomyomas, leiomyosarcomas, leiomyoblastomas, or schwannomas as a result of their histologic findings and apparent origin in the muscularis propria layer of the intestinal wall.
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GISTs have a unimodal peak incidence in persons aged 40-70 years, but they have a broad distribution.
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GIST can arise anywhere in the gastrointestinal tract (GIT), including the mesentery (Fig. 1), omentum, and retroperitoneum (very rare). About 50-70% of GISTs occur in the stomach, 33%, in the small bowel, 5-15% in the rectocolon, and only 1-5% in the esophagus. GISTs are multicentric in fewer than 5% of cases (Fig. 2).
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Fig. 1: Enhanced sagital CT scan reveals a large incidental (and very rare) mesenteric GIST, on a patient envolved on a motor-vehicle accident. References: Department of Imagiology, Hospital de São João, EPE - Porto/PT
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Fig. 2: GIST distribution in the various segments of the gastrointestinal tract. Less than 1 % of GISTs initially occur outside of these organs. References: GIST Support International. http://www.gistsupport.org/for-new-gistpatients/understanding-your-pathology-report-for-gist/pathology-analyses-for-gist.php •
GISTs are well-demarcated spherical masses that appear to arise from the muscularis propria layer of the GI wall. Intramural in origin, they often project exophytically and/or intraluminally, and they may have overlying mucosal ulceration (Fig. 3, 4, 5, 6).
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Fig. 3: Surgical piece of partial gastrectomy, fully occupied by submucosal GIST with ulcerated areas and retraction of the gastric mucosa. References: Department of Pathology, Hospital de São João, EPE - Porto/PT
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Fig. 4: Posterior view of the last image, in which one observes smooth serosa with bulging area. References: Department of Pathology, Hospital de São João, EPE - Porto/PT
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Fig. 5: Gastric GIST, after section. It features a compact cutting surface, swirled appearance and whitish in color, with foci of hemorrhage. References: Department of Pathology, Hospital de São João, EPE - Porto/PT
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Fig. 6: Gastric body GIST, detected on upper gastrointestinal endoscopy (UGE), without overlying mucosal ulceration. References: Department of Imagiology, Hospital de São João, EPE - Porto/PT •
Cytologically, GISTs can be classified into spindle cell GISTs (Fig. 7) and epithelioid GISTs (Fig. 8). Independent of location, most GISTs express the CD34 antigen (70-78%) and the CD117 (72-94%) antigen. The CD34 protein is a hematopoietic progenitor cell antigen that occurs in a variety of mesenchymal tumors. CD117 also is known as the c-kit protein; it is a membrane receptor with a tyrosine kinase component. Mutations in the CD117 gene have been linked to malignant behavior in GISTs.
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Fig. 7: Gastric GIST of moderate risk (AFIP), composed of spindle cells with mild nuclear atypia. References: Department of Pathology, Hospital de São João, EPE - Porto/PT
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Fig. 8: Gastric GIST intermediate risk (AFIP), composed of epithelioid cells with moderate nuclear pleomorphism and collagenous stroma. References: Department of Pathology, Hospital de São João, EPE - Porto/PT • 10-30% of of GISTs have malignant behavior, with 41-47% of malignant GISTs appearing metastatic on presentation (Fig. 9).
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Fig. 9: Malignant gastric GIST, metastatic on presentation - liver metastasis in the left liver lobe (visible on the same slice). References: Department of Imagiology, Hospital de São João, EPE - Porto/ PT •
GISTs rarely spread to regional lymph nodes (
