PMC4119926_01
Macroscopic appearance.
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fig1
Macroscopically, after formalin fixation, the resected specimen showed a clearly demarcated ulcer, measuring 28 x 20 mm maximum dimensions, in the ascending colon (Figure 1).
(a) SSL in the root of the appendix. (b) SSL is regionally observed in the right half of the epithelium, while nondysplastic epithelium can be observed in the left half. SSL shows the loss of hMLH-1 expression; however, a weak to moderate reactivity is preserved in the deep part of the crypts. A hMLH-1 positive control was evaluated on nondysplastic epithelium. The scale bars indicate 250 micrometers.
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fig2
The noticeable finding of this present case was the SSL which included serrated structure, crypt dilation, and horizontally arranged basal crypts, in the root of the appendix (Figure 2(a)). Concerning IHC features, the expression of hMLH-1, which is a DNA mismatch-repair protein, was absent in the SSL, although its expression was inclined to be preserved in the deeper part of crypt (Figure 2(b)).
(a) The area of gradual transition between the mucinous adenocarcinoma and SSL in the peripheral side of the appendix, but the serrated structure is not outstanding. (b) The component of mucinous adenocarcinoma without serrated structure. The scale bars indicate 500 micrometers.
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fig3
Moreover, the SSL combined with dysplastic change extended to the adjacent mucinous adenocarcinoma with an area of gradual transition (Figure 3); this SSL was pathologically regarded as a potential precursor lesion of the adjacent mucinous adenocarcinoma.