case_images: PMC9885147_01
case_images: Endoscopic appearance of the sigmoid colon tumor. (A-C) There was a polypoid tumor in the sigmoid colon, 18 cm away from the anus, with a diameter of 1.5 cm x 2 cm and with a wide base. The surface of the polyp is eroded, and the gland tube and blood vessel under (Narrow Band Imaging, NBI) are not clearly observed. But the gland tube at the base is still regular. (D, E) A little blood oozed from the wound after EMR. We applied six endoscopic hemoclips to stop the bleeding. (F) Three months after the EMR, the wound was observed to be healed well.
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case_images: PMC9885147_01_fonc-12-1026825-g002.jpg
case_images: f2
case_images: The well-circumscribed tumor was 2.0 cm in maximum diameter and had a wide base ( Figures 2A-C ). Because the tumor had a wide base, we used endoscopic mucosal resection (EMR) to remove the lesion ( Figures 2D, E ) and improve postoperative pathology. Three months after EMR, colonoscopy showed that the postoperative healing was good ( Figure 2F ).
case_images: (A) Microscopic features of the tumor at 10x magnification using microscope. The tumor consisted of nests of epithelioid cells with clear-to-eosinophilic granular cytoplasm, as pointed by arrowheads. (B) Microscopic features of the tumor at 40x magnification using microscope. The tumor cells had large nuclei with prominent nucleoli, and the local atypia of tumor cells was obvious, as pointed by arrowheads. (C) The tumor cells were immunoreactive for HMB-45, and yellow was positive in the cytoplasm, as pointed by arrowheads (at 10x magnification using microscope). (D) The tumor cells were immunoreactive for TFE-3, and yellow was positive in the nucleus, as pointed by arrowheads (at 10x magnification using microscope). (E) Ki67 immunohistochemistry at 40x magnification using microscope.
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case_images: PMC9885147_01_fonc-12-1026825-g003.jpg
case_images: f3
case_images: In our case, the nests were separated by thin fibrovascular septa ( Figure 3A ). The tumor cells had large nuclei with prominent nucleoli and the obvious local atypia of tumor cells ( Figure 3B ). The mitotic rate was >1/50HPF and about 20% of the cells expressed Ki67 ( Figure 3E ). TFE-3 ( Figure 3D ). However, they were negative for Melan-A, desmin, smooth muscle actin (SMA), S-100, CD117, and CK ( Figure 4 ). Therefore, depending on the endoscopy, histology, and immunohistochemistry results, we diagnosed the tumor as GI PEComa.
case_images: The tumor was negative for Melan-A, desmin, smooth muscle actin (SMA), S-100, CD117, and CK at 20x magnification using microscope. (A) Melan-A. (B) desmin. (C) smooth muscle actin (SMA). (D) S-100. (E) CK. (F) CD117.
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case_images: PMC9885147_01_fonc-12-1026825-g004.jpg
case_images: f4
case_images: TFE-3 ( Figure 3D ). However, they were negative for Melan-A, desmin, smooth muscle actin (SMA), S-100, CD117, and CK ( Figure 4 ). Therefore, depending on the endoscopy, histology, and immunohistochemistry results, we diagnosed the tumor as GI PEComa.