**Malignant Colorectal Polyps: Diagnosis, Treatment and Prognosis**

Luis Bujanda Fernández de Piérola, Joaquin Cubiella Fernández, Fernando Múgica Aguinaga, Lander Hijona Muruamendiaraz and Carol Julyssa Cobián Malaver

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/52697

**1. Introduction**

Adenomatous polyps are non-invasive tumours of epithelial cells arising from the mucosa with the potential to become malignant. The adenoma-carcinoma sequence is well known and it is accepted that more than 95% of colon adenocarcinomas arise from adenoma [1]. The World Health Organisation (WHO) classifies adenomas into tubular (<20% villous ar‐ chitecture), tubulovillous and villous (80% villous architecture), with approximately 87% of adenomas being tubular, 8% tubulovillous and 5% villous [2].

**Figure 1.** Polyp in colon

© 2013 de Piérola et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Only 5% of adenomas are in danger of becoming malignant. The probability of high grade dysplasia and carcinomatous transformation increases with polyp size, a villous component, when there are many polyps or the age at diagnosis is more than 60 years [2]. The neoplasia is considered to be advanced when polyp size is 1 cm or more, there is a villous component or a high degree of dysplasia. Mixed polyps also have the ability to become malignant, as does hyperplastic polyposis syndrome. More than 25% of advanced polyps are located in the area proximal to the splenic flexure [3].

amount of lamina propria, and is cytologically identical to the overlying adenomatous com‐ ponent. Hemorrhage and hemosiderin depositions, are commonly seen and are a clue to di‐ agnosis. In addition, inflammation and granulation tissue, can be found.Cystic dilatation of the displaced glands with mucin distention is also not uncommon in pseudoinvasion be‐ cause mucin produced by the entrapped glands has no means of reaching the lumen. Occa‐ sionally, rupture of dilated glands occurs with acellularmucin extravasation and there is a subsequent inflammatory response. Distinction from mucinous (colloid) carcinoma is im‐ portant and can be difficult. Specifically, in mucinous carcinoma, the mucin pools contain

Malignant Colorectal Polyps: Diagnosis, Treatment and Prognosis

http://dx.doi.org/10.5772/52697

125

For these reasons, it is highly recommended that level sections and second opinions, are ob‐

All adenomas have some degree of dysplasia. However, low and high grade dysplasias are artificial subdivisions of a spectrum. There is no definition of "high-grade". Indeed, the WHO book on tumors of the digestive system, does not contain a list of criteria for highgrade dysplasia in adenomas [15,16]. However in general, high-grade dysplasia entails more substantial changes and includes carcinoma "in situ". Among these changes we consider ar‐ chitectural alteration, often resembling the glandular arrangement of adenomas and cyto‐ logic abnormalities, principally cellular and nuclear pleomorphism, nuclear hyperchromatism, loss of nuclear polarity, and marked stratification of nuclei. Other au‐ thors have considered as features of high grade displasia: loss of normal glandular architec‐ ture, hyperchromatic cells with multilayered irregular nuclei and loss of mucin, high nuclear/cytoplasmic ratio, marked nuclear atypia with prominent nuclei and focal cribri‐ form patterns. Not all these features are necessarily present to the same degree in all dys‐ plastic epithelia, while low-grade dysplasia manifests these same changes but to a lesser

Many factors have been associated with a higher probability of residual disease or recurrent

Morphology is described as polypoid (pedunculated or sessil) and nonpolypoid (flat or ul‐ cerated) subtypes according to the Paris classification [17]. The type of polyp and its mor‐ phology can guide the endoscopist towards its potential malignancy [2,18,19]. These features include the size, the presence of depressed ulceration, irregular contours, deformi‐ ty, a short and immobile stalk and the inability to elevate a sessile polyp when a submucosal bleb is formed. In such suspicious lesions, as well as in flat or depressed lesions, diagnosis can be carried out using chromoendoscopy and magnification techniques that can highlight abnormalities of glandular cytoarchitecture and reveal information concerning the extent of

malignant cells, a feature lacking in pseudoinvasion.

degree [15,16].

carcinoma.

**4.1. Morphology**

**4. Prognostic factors**

submucosal invasion [20,21].

tained in cases of polyps with potential pseudoinvasion [14].
