PMC5299978_01
(A) Colonoscopic finding showing a mixed-nodular type laterally spreading tumor measuring 5.6 cm in diameter. (B) Gross endoscopic submucosal dissection (ESD) specimen of the primary lesion. (C) Pathological findings for the ESD specimen showing multiple foci of adenocarcinoma component in the bulky laterally spreading adenoma. The least-differentiated component is highlighted by a dashed line (H&E stain, x10). Higher magnification of the least-differentiated area, showing solid and cribriform architecture and multiple foci of the invasive front, consisting of small, infiltrative tumor glands (arrowheads) (inset: H&E stain, x200). (D) Follow-up sigmoidoscopy in 8 months shows a scar. (E) Sigmoidoscopy performed 17 months after ESD, showing mucosal elevation with central ulceration at the previous procedure site, which is suggestive of extrinsic infiltrative cancer. (F) Endoscopic biopsy obtained from the previous ESD site, showing a poorly differentiated adenocarcinoma sitting under normal colonic crypts (H&E stain, x100). Needle biopsy specimen of a pulmonary metastasis showing similar morphology of tumor glands to that of the previous ESD specimen in terms of solid and cribriform architecture (inset: H&E stain, x200).
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A 67-year-old woman underwent ESD for a 5.6-cm mixed-nodular type laterally spreading tumor (LST) in the rectum (Fig. 1A, B). The histology showed a well-differentiated adenocarcinoma confined to the LP without lymphovascular invasion and with clear resection margins (Fig. 1C). Follow-up sigmoidoscopy at 8 months showed only a scar (Fig. 1D). Sigmoidoscopy showed an extrinsic infiltrative lesion at the previous ESD site (Fig. 1E). The pathological findings of the previous ESD site lesion revealed a poorly differentiated adenocarcinoma under normal colonic crypts (Fig. 1F). The histology of lung nodules (Fig. 1F, inset) showed a poorly differentiated adenocarcinoma that was positive for cytokeratin 20 and negative for cytokeratin 7 on immunohistochemistry, suggesting pulmonary metastasis of enteric type adenocarcinoma. At low magnification, the bulky, laterally spreading adenoma contained multiple foci of adenocarcinoma component (Fig. 1C). Higher magnification of the least differentiated area showed solid and cribriform architecture and multiple foci of the invasive front, consisting of small, infiltrative tumor glands (Fig. 1C, inset).
PMC5299978_02
(A) Colonoscopic finding showing a mixed-nodular type laterally spreading tumor measuring 6.0 cm in diameter. (B) Severe cauterization at the margin and the middle of the tumor is suspected in the endoscopic image (arrows). (C) Pathological findings for the endoscopic submucosal dissection (ESD) specimen showing a laterally spreading adenoma with a frankly invasive adenocarcinoma component (dashed line, H&E stain, slide scan without magnification). At higher magnification, invasive tumor cells form large, irregularly shaped tubules and have occasional goblet cells. The surrounding stroma is desmoplastic (inset: H&E stain, x200). (D) Follow-up colonoscopy at 12 months shows only a scar. (E) Colonoscopy at 34 months after ESD shows an ulcerofungating mass that encircles the lumen at the previous ESD site. (F) Pathological findings of resected tumor show an "undermining" invasion pattern without surrounding mucosal change (H&E stain, x10). The cytomorphology of the resected tumor is similar to that of the invasive component of the previous ESD specimen (inset: H&E stain, x200).
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A 62-year-old woman underwent en bloc ESD for a 6-cm, mixed-nodular LST in the ascending colon (Fig. 2A, B). The histological examination showed a laterally spreading adenoma with a small fraction of moderately differentiated adenocarcinoma component (Fig. 2C, dashed line). At higher magnification, the invasive tumor cells formed large, irregularly shaped tubules and had occasional goblet cells, and the surrounding stroma was desmoplastic (Fig. 2C, inset). As expected in the endoscopic findings (Fig. 2B, arrowheads), the resection margins showed severe cautery artifact and low-grade dysplasia involved the resection margins. Follow-up colonoscopy at 12 months showed only a scar (Fig. 2D). Colonoscopy showed an ulcerofungating mass encircling the lumen at the previous ESD site (Fig. 2E). Furthermore, surrounding mucosa and mucosal "islands" in the ulcer base did not show any preneoplastic changes (Fig. 2F). At higher magnification, the cytomorphology of the resected tumor was similar to that of the invasive component of the previous ESD specimen (Fig. 2F, inset).