Clinical and Molecular Characteristics of Rare Malignant Tumors of Colon and Rectum

Abstract

The most frequent form of colorectal cancer is represented by adenocarcinoma being about 98% of tumor histological types. However, other rare histotypes can be found in colon and rectum (adenosquamous, goblet cell adenocarcinoma, lymphoma, medullary carcinoma, melanoma, mesenchymal, neuroendocrine, plasmacytoma, signet ring, squamous tumors). Altogether, these forms account for less than 2% of colorectal tumors. There are no specific diagnostic or therapeutic recommended approaches and most of the information available from literature derives from small and retrospective clinical series. In the present study, we provide a paramount and updated view on clinical and biologic characteristics of rare colorectal tumors.

Keywords: NGS; colon; genetics; rare tumors; rectum.

Figure 1

Representation of percentage of distribution of all colorectal cancers through pie chart (given a total frequency equal to 100) (A). Representation of percentage of distribution of rare forms of colorectal cancers (given a total frequency of rare forms equal to 100) (B). Different histotypes are indicated with colors in legends besides the pie charts. Data are extracted and elaborated from the American Cancer Society (Cancer Facts and Figures 2010. Atlanta: American Cancer Society; 2010).

Figure 2

Anatomical site representation of predominant localization (as derived from the analysis of the clinical series analyzed in the present work).