Author: PathologyMCQ Editorial Team
Category: Gastrointestinal Pathology – Serrated Colorectal Polyps
Last Updated: October 2026
Read Time: 12 minutes
Difficulty: Moderate (MD/DNB, FRCPath, NEET-SS)
At a glance
- What: the commonest serrated colorectal polyp; small, sessile and usually in the rectum and sigmoid colon.
- Diagnostic rule: serration confined to the upper half of the crypts, with straight, narrow crypt bases and no dysplasia.
- Two WHO subtypes: microvesicular (often BRAF V600E) and goblet cell-rich (often KRAS); the mucin-poor subtype is no longer used.
- Key mimic: the sessile serrated lesion, diagnosed by even one architecturally distorted crypt base.
- In this post: a 5-tab virtual slide viewer (both subtypes, SSL, TSA and gastric hyperplastic polyp), an annotated slide, comparison tables and 10 interactive MCQs including 5 slide-based questions.
What is a hyperplastic polyp?
A hyperplastic polyp is a benign serrated epithelial polyp of the large bowel. It results from delayed shedding of surface epithelial cells, which pile up and give the upper crypts their saw-tooth outline, while the proliferative zone at the crypt base stays normal. Most are under 5 mm, pale and flat to sessile, found incidentally at screening colonoscopy in adults over 50, and are commonest in the rectum and sigmoid colon. Small distal hyperplastic polyps carry no meaningful cancer risk.
Microscopic features
- Serration in the upper half: a saw-tooth or stellate luminal outline in the superficial crypts and surface.
- Straight crypt bases: narrow, evenly spaced and perpendicular to the muscularis mucosae, with no dilatation, branching or horizontal growth.
- Normal proliferative zone: small, basally located nuclei with mitoses confined to the lower crypt.
- Thickened subepithelial collagen is common under the surface; it is not collagenous colitis.
- No dysplasia: crowded, elongated, hyperchromatic nuclei rule out a hyperplastic polyp.
Microvesicular vs goblet cell-rich subtypes
| Feature | Microvesicular HP (MVHP) | Goblet cell-rich HP (GCHP) |
|---|---|---|
| Frequency | Commonest subtype | Less common |
| Serration | Prominent saw-tooth pattern in the upper crypts | Mild, mostly at the surface |
| Epithelium | Columnar cells with fine microvesicular mucin; fewer goblet cells | Crypts lined mainly by goblet cells |
| Site | Throughout the colon, commonest distally | Mostly distal colon and rectum |
| Molecular | Often BRAF V600E, CpG island methylation | Often KRAS |
| Serrated pathway | Thought to be a precursor of sessile serrated lesions | Not a recognised precursor |
Compare the subtypes on real slides: the virtual slide viewer below has both hyperplastic polyp subtypes next to a sessile serrated lesion, a traditional serrated adenoma and a gastric hyperplastic polyp.
Virtual slides · real cases
Hyperplastic polyps and the serrated look-alikes
Follow the crypts from surface to base on each slide: where the serration stops, and what the base does, makes the diagnosis.
What to look for
Drag to pan · pinch or double-tap to zoom · use the + / − buttons
Annotated slide
Use the region selector to jump to the labelled features of the goblet cell-rich hyperplastic polyp.
Hyperplastic polyp, colon
Hyperplastic polyp vs SSL vs TSA
| Feature | Hyperplastic polyp | Sessile serrated lesion | Traditional serrated adenoma |
|---|---|---|---|
| Usual site | Rectum and sigmoid | Proximal colon | Distal colon |
| Serration | Upper half of crypts | Extends to the crypt base | Slit-like, along villi |
| Crypt base | Straight and narrow | Dilated, L- or inverted T-shaped, horizontal along the muscularis mucosae | Ectopic crypt foci that do not reach the muscularis mucosae |
| Cells | Microvesicular or goblet cells | Similar to HP, sometimes with mild basal atypia | Tall columnar cells, eosinophilic cytoplasm, pencillate nuclei |
| Dysplasia | None | Absent, or abrupt intestinal or serrated dysplasia (not graded) | Intrinsically dysplastic (low grade); may progress |
| Molecular | BRAF (MVHP) or KRAS (GCHP) | BRAF V600E, CIMP; MLH1 methylation in dysplasia | KRAS or BRAF; RSPO fusions in a subset |
| Diagnostic threshold | All crypts typical | One unequivocal distorted crypt is enough; size is not a criterion | Overall architecture and cytology |
Large (10 mm or more) or proximal “hyperplastic polyps” deserve a second look, with deeper levels if needed, because many turn out to be sessile serrated lesions once well-oriented crypt bases are seen.
Serrated polyposis syndrome
| WHO criterion | Definition |
|---|---|
| Criterion 1 | At least 5 serrated lesions or polyps proximal to the rectum, all at least 5 mm, with at least 2 measuring 10 mm or more |
| Criterion 2 | More than 20 serrated lesions or polyps of any size throughout the large bowel, with at least 5 proximal to the rectum |
Hyperplastic polyps, sessile serrated lesions and traditional serrated adenomas all count, and counts are cumulative across colonoscopies. Patients need colonoscopic surveillance, and first-degree relatives have an increased colorectal cancer risk.
Gastric hyperplastic polyp
- A separate entity from the colorectal hyperplastic polyp, sharing only the name.
- Background: chronic gastritis, particularly Helicobacter pylori and autoimmune atrophic gastritis; also near anastomoses and erosions.
- Histology: elongated, tortuous and cystically dilated foveolar pits in an oedematous, inflamed lamina propria, often with surface erosion.
- Risk: small risk of dysplasia and carcinoma, mainly in polyps larger than 1 cm; biopsy the background mucosa and treat H. pylori.
Management and surveillance
- Polypectomy is curative for a hyperplastic polyp.
- Small distal hyperplastic polyps (under 10 mm): no increased risk; the patient returns to routine screening.
- Hyperplastic polyps of 10 mm or more: a shorter surveillance interval is usually advised, and the pathology should be reviewed to exclude a sessile serrated lesion.
- Multiple or large proximal serrated polyps: check the serrated polyposis criteria.
Featured course · Ultimate FRCPath Part 2 Study Program
Serrated polyps are FRCPath favourites. Report them with confidence.
The FRCPath Part 2 program trains you on the cases examiners set: GI short surgicals, polyp biopsies and the reporting decisions that separate a pass from a fail.
- GI and colorectal short surgicals with model answers
- Long cases, macros and virtual slide practice
- Exam-day reporting technique from practising pathologists
Test yourself: 10 MCQs
5 slide-based questions (both HP subtypes, SSL and TSA) plus 5 on molecular pathology, serrated polyposis, gastric HP and surveillance. Tap an answer for the explanation.
More practice: the full quiz is below, and the GI pathology MCQ bank →
More practice: hyperplastic polyp quiz
Exam pearls and key takeaway
- Hyperplastic polyp: serration in the upper crypts, straight narrow bases, no dysplasia.
- Subtypes: microvesicular (BRAF) and goblet cell-rich (KRAS); mucin-poor is no longer used.
- SSL: one unequivocal distorted crypt base is enough; size does not count.
- TSA: ectopic crypt foci, slit-like serrations and tall eosinophilic cells.
- Gastric hyperplastic polyp is a separate entity linked to chronic gastritis.
- Key takeaway: follow each crypt to its base. A large or proximal “hyperplastic polyp” is a sessile serrated lesion until well-oriented bases prove otherwise.
Go further
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The Pathology MCQ app
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Daily MCQ with streaks, pinch-zoom virtual slides with annotations, and your courses in one place.
Related reads: Serrated polyps of the intestine: a complete guide → · Hamartomatous polyps → · GI pathology MCQs →
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