J Korean Soc Radiol.  2014 Nov;71(5):239-248. 10.3348/jksr.2014.71.5.239.

Correlation between Computed Tomography and Pathological Findings of Gastrointestinal Stromal Tumors Treated with Imatinib Mesylate

• Sim KC
• Park BJ
• Han NY
• Sung DJ
• Kim MJ
• Cho SB
• Ha HK
• Kim HR

• KMID: 2208793
• DOI: http://doi.org/10.3348/jksr.2014.71.5.239

Abstract

PURPOSE
To evaluate the correlation between pathological and computed tomography (CT) findings of gastrointestinal stromal tumors (GISTs) after imatinib mesylate (imatinib) treatment.
MATERIALS AND METHODS
Twenty-six patients with GIST (17 men, 9 women; mean age, 56 years) who underwent treatment with imatinib and who were registered at our institution were included. Eight patients had primary and 18 had metastatic tumors. The correlation between CT and pathological findings was evaluated for all 26 tumors, which were resected after imatinib treatment.
RESULTS
The mean size change in the tumors after imatinib treatment was -1.4 cm (range, -7.8-2.5 cm). A reduction in tumor CT attenuation value was observed after imatinib treatment (mean, 29.1 Hounsfield units) in 20 of 26 tumors. Reduced attenuation was associated with non-tumorous pathological findings, including cystic degeneration (6/20), hemorrhagic necrosis (6/20), hyaline degeneration (6/20), and combined pathology without a viable portion (2/20). Of six tumors showing increased attenuation values after treatment, four (66.7%) showed an abundant viable portion. The increase in tumor size was not associated with the presence of a viable portion in any tumor.
CONCLUSION
CT attenuation changes in GISTs may adequately reflect the pathological findings in GISTs after imatinib treatment.

MeSH Terms

Female
Gastrointestinal Stromal Tumors*
Humans
Hyalin
Male
Mesylates*
Necrosis
Pathology
Imatinib Mesylate
Mesylates

Figure

• 

  Fig. 1 Transverse CT scans of a gastrointestinal stromal tumor before and after imatinib treatment in a 36-year-old man. CT attenuation was measured by adjusting the rectangular region of interest to encompass as much as possible of the portion showing a significant change in CT findings before and after imatinib treatment. A. Solid mass with lobulated contour abutting the small bowel before imatinib treatment. B. Six months after imatinib treatment, the attenuation of the solid tumor had decreased, and a peripheral wall and internal septation were apparent. C. Gross specimen showing the resected small bowel and large bowel loops with the chamber of cystic degeneration (solid arrow). D. Microscopic examination revealed extensive multiloculated cystic degeneration (Cy) with an internal septum containing viable tumor cells (Vi) (H&E stain, × 20).

• 

  Fig. 2 Transverse CT scans of a primary gastrointestinal stromal tumor (GIST) of the small bowel in a 53-year-old man. A. A CT scan before imatinib treatment shows a heterogeneous low attenuated mass abutting pelvic ileal loops. B. CT scans obtained 18 months after imatinib treatment showed a lesion with reduced attenuation, suggestive of a cyst-like component with an intramural nodule (solid arrow). C. Photograph of a resected and opened GIST from the ileum showing a central cavity in the gross specimen. D. Microscopic examination revealed extensive hemorrhagic necrosis (HN) (H&E stain, × 40).

• 

  Fig. 3 Transverse CT scans of a splenic metastasis from a gastrointestinal stromal tumor of the stomach in a 62-year-old woman. A. A CT scan before imatinib treatment reveals a heterogeneous, hypo-attenuated metastatic lesion in the spleen. B. A CT scan obtained 28 months after imatinib treatment. The metastatic spleen lesion is nearly resolved, and the cystic lesion including ascites and fluid collection has developed next to the spleen (open arrow). C. Photomicrograph of the resected spleen. Hyaline changes owing to ascites or fluid collection outside the splenic capsule (solid arrows) and splenic parenchyma (*) are not a true cystic degeneration but extensive hyalinization (Hy) (H&E stain, × 20).

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  Fig. 4 Transverse CT scans of a primary gastrointestinal stromal tumor (GIST) of the stomach in a 68-year-old man. A. A CT scan before imatinib treatment showed a heterogeneously attenuated GIST arising in the stomach. B. A CT scan obtained 27 months after imatinib treatment reveals a homogenous lesion with reduced attenuation and extensive internal calcification (solid arrow). The dominant gross and microscopic pathological finding was of hyalinization with abundant calcification.

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  Fig. 5 Transverse CT scans of omental metastasis from gastrointestinal stromal tumor of small bowel in 64-year-old woman. A. A CT scan before imatinib treatment showing highly attenuated heterogeneous round mass beside hepatic flexure of the colon (solid arrow). B. A CT scan 14 months after imatinib treatment reveals a metastatic lesion (solid arrow). The size has decreased with an increase of homogeneity in internal attenuation. C. Gross specimen of resected omental mass showing solid mass with minimal internal hemorrhage in the cut surface. D. Photomicrograph of resected omental mass showing spindle-shaped hypercellular viable tumor (Vi) in most part of tumor with interspersed hyalinization (Hy). The viable tumor portion and the interspersed hyalinization with scanty hemorrhage occupied in about 75% and 25% of the tumor, respectively (H&E stain, × 100).

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