Which histologic feature is commonly seen in colorectal adenocarcinoma compared with benign polyps?

Which histologic feature is commonly seen in colorectal adenocarcinoma compared with benign polyps?

• A. Invasion through muscularis mucosae into submucosa or beyond
• B. Confined to mucosa
• C. Absence of cytologic atypia
• D. Lack of desmoplastic stroma

Answer: (A)

Invasion through the muscularis mucosae into the submucosa or beyond is the defining feature that separates invasive colorectal adenocarcinoma from benign polyps. Benign polyps, including hyperplastic polyps and adenomas, are confined to the mucosa and do not breach the muscularis mucosae. Once tumor cells penetrate into the submucosa (or deeper), it becomes invasive cancer with malignant potential, and this invasion depth is crucial for staging. That’s why this feature is the best choice. The other options describe states that are not characteristic of invasive cancer: staying confined to the mucosa fits benign lesions or noninvasive neoplasia; lack of cytologic atypia would be unusual for carcinoma (which typically shows atypia); and while desmoplastic stroma can accompany invasion, its absence isn’t what defines invasion and carcinoma.

Invasion through the muscularis mucosae into the submucosa or beyond is the defining feature that separates invasive colorectal adenocarcinoma from benign polyps. Benign polyps, including hyperplastic polyps and adenomas, are confined to the mucosa and do not breach the muscularis mucosae. Once tumor cells penetrate into the submucosa (or deeper), it becomes invasive cancer with malignant potential, and this invasion depth is crucial for staging.

That’s why this feature is the best choice. The other options describe states that are not characteristic of invasive cancer: staying confined to the mucosa fits benign lesions or noninvasive neoplasia; lack of cytologic atypia would be unusual for carcinoma (which typically shows atypia); and while desmoplastic stroma can accompany invasion, its absence isn’t what defines invasion and carcinoma.