Adenoma of the Colon and Rectum
Grading / Staging / Report
- Grading
- Dysplasia of adenomas should be graded
- Adenomas by definition have at least low grade dysplasia
- Low grade dysplasia thus need not be addressed in the report for the typical adenoma
- Moderate dysplasia is not an accepted term
- Anything less than high grade should be termed low grade
- The term moderate dysplasia has no accepted meaning and risks giving an unclear clinical message
- High grade dysplasia is characterized by any one of the following:
- Cribriform architecture
- Back to back gland lumens without intervening stroma
- Should clearly be a manifestation of total loss of polarity by atypical cells
- Frequently, well differentiated mucin producing cells will pile up, forming lumens, technically appearing cribriform
- Nuclei show regular basal orientation
- Nuclei typically not markedly enlarged
- This should not be considered high grade dysplasia
- Severe cytologic atypia
- This is unusual in the absence of cribriform architecture, but can occur
- Invasion with a desmoplastic response
- Invasion confined to the lamina propria including muscularis mucosae is designated high grade intramucosal neoplasia
- At other GI sites this is considered intramucosal carcinoma
- If that term is used for colorectal lesions, the report should make it clear that it represents an in situ lesion
- Significance of high grade intra-mucosal invasive carcinoma is a subject of current debate
- In a series of 15 such cases, all appeared to be adequately treated by polypectomy (Lewin 2007)
- Two cases exhibiting aggressive features have subsequently been reported (Shia 2008)
- Use TNM staging if high grade dysplasia or invasive carcinoma are present
