Architectural patterns of growth of colon adenocarcinoma - comparative study

Colorectal adenocarcinoma (CR ADK) may show either a uniform architectural pattern or intratumoral architectural heterogeneity, but the clinicopathological relevance of these growth patterns is still insufficiently characterized.

The study's aim was to compare the clinical and morphological profiles of tumors with a single dominant architectural pattern and tumors with two coexisting architectural patterns.

We analyzed 104 CR ADKs, divided into two groups: one group of 78 patients with a single architectural pattern all over the tumor and one group of 26 patients with two architectural patterns within the tumor. Clinical parameters and morphological parameters (macroscopic and microscopic) were comparatively assessed using, for categorical variables, the χ² (chi-squared) test and, for continuous variables Student's t-test.

Tumors with a single morphological appearance were found in males of around 65 years old, from urban areas, located especially in the distal regions of the colon, usually circumferential and greater than 5 cm. Morphologically, they were usually fungated and ulcerative common forms of ADK with moderate degree of differentiation and, overall, with a somewhat less aggressive biological behavior. Tumors with two morphological aspects, in turn, were found often in old women, in the proximal regions of the colon and most often circumferential but with smaller dimensions than those in the first group. Morphologically, they were usually protrusive with ulcerations on the surface. Although the usually encountered patter was that of common form of well-differentiated ADK, in the deep areas, they assumed poorly differentiated forms, most often with mucinous-type secretory properties. Aggressiveness markers like intratumor necrosis or inflammation were a common presence. The biological behavior was more aggressive, especially with the invasion of regional lymph nodes.

Our study identified a subgroup of colon epithelial malignancies with two main architectural patterns that presented distinctive clinical-morphological features and a trend toward greater biological aggressiveness, particularly through deeper mucinous∕poorly differentiated transformation and more frequent necro-inflammatory changes. Further studies are necessary to include this tumor profile in routine prognostic assessment of colorectal epithelial malignancies.