PMC5949200_01
Endoscopic images of Case 1. A pedunculated polyp covered with intact mucosa is observed (a, b). Resected polyp is 10 mm in diameter and 14 mm in length (c).
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fig1
Colonoscopy revealed an oval-shaped pedunculated polyp at the splenic flexure of the transverse colon (Figure 1). The surface of the polyp was covered with intact mucosa; regularly arranged round pits were observed under magnification (Figure 1(a)). The resected polyp was 10 mm in diameter and 14 mm in length (Figure 1(c)).
Pathological images of Case 1. A tumor composed of eosinophilic cells is observed. The tumor is covered with normal appearing mucosa ((a), hematoxylin and eosin staining, x40). The tumor cells have relatively uniform nuclei, abundant cytoplasm, and indistinct cell boundaries. Mitoses are rarely observed ((b), hematoxylin and eosin staining, x400). The cells are positive for alpha-SMA ((c), x40) and desmin ((d), x40).
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fig2
Histologically, dense proliferation of spindle cells was observed in the submucosal layer (Figures 2(a) and 2(b)). The cells were positive for alpha-smooth muscle cell actin (alpha-SMA, Figure 2(c)) and desmin staining (Figure 2(d)) but were negative for c-kit, S-100, or DOG-1 staining.
PMC5949200_02
Endoscopic images of Case 2. The surface of the polyp head is ulcerated (a). The polyp is of pedunculated form (b). The unulcerated part of the polyp shows intact pit structure after indigo carmine spraying (c). Narrow-band imaging (d).
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fig3
A pedunculated polyp, 40 mm in diameter and 40 mm in length, was identified at the hepatic flexure of the colon during colonoscopy (Figures 3(a) and 3(b)). The surface of the polyp was ulcerated and covered with a white substance (Figure 3(a)). Although the mucosa of the unulcerated parts of the polyp was partly swollen, the pit structure was mostly normal and round; this was emphasized after indigo carmine spraying (Figure 3(c)). Narrow-band imaging, under magnification, also showed partial swelling of the surface structure (Figure 3(d)).
Pathological images of Case 2. Spindle cells with round to oval nuclei are observed in the resected specimen ((a), x4, (b), x400). The tumor cells are positive for alpha-SMA ((c), x100) and desmin ((d), x100).
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fig4
Histological analysis revealed a dense proliferation of spindle cells with round to oval nuclei beneath the thin, normal mucosal epithelium (Figures 4(a) and 4(b)). Tumor cells were positive for alpha-SMA (Figure 4(c)) and desmin (Figure 4(d)) but were negative for c-kit, S-100, or DOG-1.