PMC9970808_01
MRI findings of EGIST. A: MRI showed a lobulated mass in the space between the stomach and pancreas that was well-demarcated. B: MRI showed an irregular mass in the right posterior lobe of the liver with an uneven high signal.
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T1/T2 signal with uneven arterial lesion enhancement (Fig. 1A). There were multiple nodules of different sizes in the right abdominal wall, greater omentum, lower abdomen and pelvic cavity that also seemed to be unevenly enhanced. Under the liver parenchyma and capsule, there were multiple masses, the biggest of which was located in the right posterior lobe (73x55 mm), and some lesions protruded outside the liver (Fig. 1B); all of these lesions were considered likely to be malignant and metastatic.
CT findings of EGIST. A: Enhanced CT showed an abdominal mass with uneven enhancement and no enhanced necrotic area. B: Coronal multiplanar reconstruction showed a lobulated mass in the lower abdominal mesenteric areas.
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Enhanced computed tomography (CT) revealed that the abdominal mass was unevenly enhanced, with no enhanced necrotic area, while the lesions in the lower segment of the right posterior lobe of the liver showed mild to moderate uneven enhancement (Fig. 2A). Coronal multiplanar reconstruction showed a lobulated mass in the lower abdominal mesenteric area, with moderately uneven enhancement, pushing against the surrounding small intestine and compressing the bladder (Fig. 2B).
Histopathological features of EGIST by a puncture biopsy guided by B-ultrasound (Hematoxylin and Eosin staining, x200). A: The cells were oval-shaped with plasmoid characteristics in the abdominal tumor. B: Similar to the abdominal tumor, the metastatic cells of the liver showed plasmoid morphology.
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As a result of the unclear nature of the tumor, a B-ultrasound-guided biopsy was performed for the left upper abdominal mass (Fig. 3A) and liver mass (Fig. 3B), both of which showed the same morphology on Hematoxylin and Eosin (H&E) staining microscopically.
Immunohistochemical staining of EGIST (Envision, x100). A: The tumor cells were positive (+) for CD117. B: The tumor cells were strongly positive (++) for CD34. C: The tumor cells were positive (+) for DOG1. D: The Ki-67 index was about 5%.
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CD117 (Fig. 4A); CD34 (Fig. 4B), succinate dehydrogenase B (SDHB), vimentin and DOG1 (Fig. 4C) were partially positive; smooth muscle actin (SMA) was focally positive; and the Ki-67 labeling index was 5% (Fig. 4D). Cells were completely negative for cytokeratin (CK), low cytokeratin (L-CK), synaptophysin (Syn), chromogranin A (CgA), HMB45, S-100, CD38, CD138, kappa light chain (kappa), lambda light chain (lambda), Fli-1, TEF3 and CD99.