1. The Malignant Colon Polyp: Diagnosis and Therapeutic Recommendations
Marie E. Robert 
Clinical Gastroenterology and Hepatology 
Volume 5, Issue 6, Pages (June 2007)
DOI: /j.cgh
Copyright © 2007 AGA Institute Terms and Conditions

2. Figure 1
Optimal sectioning of intact polyps. Cutting the polyp in the center of the stalk allows the most thorough examination of the mucosa/submucosa junction and the stalk margin. Modified from Cranley et al.5
Clinical Gastroenterology and Hepatology 2007 5, DOI: ( /j.cgh )
Copyright © 2007 AGA Institute Terms and Conditions

3. Figure 2
(A) Low-power view of the center of the snared polyp. The surface is a villous adenoma. In the center of the lesion invasive carcinomatous glands are present in the submucosa (arrows) and approach the cauterized margin. (B) On high power, a tumorous gland is seen very near the cauterized biopsy margin (arrows). The tumor itself shows cautery artifact. The distance between the tumor and the margin is less than 1 mm. This is considered a positive margin.
Clinical Gastroenterology and Hepatology 2007 5, DOI: ( /j.cgh )
Copyright © 2007 AGA Institute Terms and Conditions

4. Figure 3
(A) Limitations of snare polypectomy for malignant polyps. The lesion on the left is treated adequately by polypectomy alone, whereas the lesion on the right will require colectomy because of a positive margin. Modified from Haggitt et al.8 (B) Poorly differentiated carcinoma. This high-power view shows the cytologic detail of a malignant polyp with mucinous features (mucinous carcinoma). Notice the lack of recognizable gland formation, a feature of poorly differentiated tumors. The tumor cells form nests and float in mucin pools (arrows). (C) The same lesion as that shown in B. The mucinous carcinoma is present at the biopsy margin (arrow).
Clinical Gastroenterology and Hepatology 2007 5, DOI: ( /j.cgh )
Copyright © 2007 AGA Institute Terms and Conditions

5. Figure 4
(A) Lymphatic invasion is rare and difficult to identify with certainty in malignant polyp specimens. In this example, a solid nest of tumor cells is present in a space that appears to be lined by endothelial cells (arrow). This appearance is characteristic of lymphatic (or capillary) invasion and is an indication for colectomy when found. (B) This high-power view of a factor VIII–stained slide reveals that the clump of tumor cells is indeed lying within a vascular space. The cells lining the structure are factor VIII positive, identifying them as endothelial cells (arrow).
Clinical Gastroenterology and Hepatology 2007 5, DOI: ( /j.cgh )
Copyright © 2007 AGA Institute Terms and Conditions

6. Figure 5
(A) Pseudoinvasion. This low-power view of a pedunculated adenoma reveals intramucosal carcinoma. In addition, several rounded nests of glands appear to be beneath the muscularis mucosa and lay within the superficial submucosa (arrows). (B) On high power, the nests within the submucosa are surrounded by lamina propria–type inflammatory cells (arrows). In addition, the glands are identical histologically to those found in the mucosa immediately above. Note the dilated and congested vessels nearby. Other areas revealed hemosiderin-laden macrophages. These features are characteristic of pseudoinvasion.
Clinical Gastroenterology and Hepatology 2007 5, DOI: ( /j.cgh )
Copyright © 2007 AGA Institute Terms and Conditions