What are the histologic features of conventional adenomas?
- Tubular adenomas have a tubular architecture with the surface epithelium showing low-grade dysplasia that extends downward in the base.
- These can show focal areas of high-grade dysplasia with architectural complexity and marked cytologic atypia.
- Focal high-grade dysplasia does not have a metastatic potential.
- The tubulovillous adenomas show a combination of tubular and villous architecture (villous component greater than 25%).
- Villous adenoma displays a predominant villous architecture (greater than 75%) and has a greater propensity for malignant transformation.
- All of these can have focal areas of pseudoinvasion that should not be interpreted as intramucosal carcinoma.
- The conventional adenomas show KRAS mutations ( BRAF negative).
