Hyperplastic Polyp of the Colon and Rectum
Differential Diagnosis
| Hyperplastic Polyp |
Tubular Adenoma |
| Lacks cytologic dysplasia |
Requires cytologic dysplasia |
| Proliferative zone restricted to base |
Proliferative zone starts at the surface |
| Gland lining cells mature at the surface |
No surface maturation |
Deep proliferative zone of HP can resemble TA; the surface must be examined to make the distinction in many cases
| Hyperplastic Polyp |
Sessile Serrated Polyp / Adenoma |
| ≥90% of bases of crypts straight, regular, narrow, frequently pointed, no dilated flattened bases |
1 to 3 crypts required with basal dilation and flattening, bases boot or inverted T shaped, <90% of bases are narrow |
| Proliferative zone reliably restricted to base |
Bases contain mature mucous cells |
| Serrations and CK20+ maturation limited to luminal 2/3 of crypt |
Serrations and CK20+ patches of maturation can be seen at all levels |
| Predominantly left sided and small |
Predominantly right sided and frequently ≥1 cm |
Polyps with mixed or intermediate features are designated indeterminate (e.g. between 50-90% narrow crypts and/or <3 flat crypt bases)
| Traditional Serrated Adenoma |
Hyperplastic Polyp |
| Cytologic dysplasia throughout |
Lacks cytologic dysplasia |
| Typically complex architecture |
Crypts are vertically arranged and not complex |
| Multiple ectopic crypt foci (short disoriented crypts not reaching the muscularis mucosae) |
Crypts each span from lumen to muscularis mucosae |
