Subtitle: How to tell Paneth cells from neuroendocrine cells in a colonic biopsy: granule position, where Paneth cells are normal, when they mean chronic injury, immunostains and 10 MCQs.
Author: PathologyMCQ Editorial Board
Category: GI Pathology
Last Updated: October 2026
Read Time: 6 minutes
At-a-Glance
- Both have eosinophilic granules. The key is where they sit: Paneth cell granules are coarse and apical (above the nucleus); neuroendocrine granules are fine and basal (below the nucleus).
- Paneth cells are normal in the small bowel and the right colon (caecum and ascending colon).
- Paneth cells beyond the hepatic flexure are metaplastic and mean chronic mucosal injury, in either ulcerative colitis or Crohn’s disease.
- Neuroendocrine cells are normal throughout the gut; chromogranin and synaptophysin confirm them.
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Spot the Difference
On H&E at high powerLook at where the granules sit
Paneth cellApical, coarseSupranuclearLarge, bright red, refractile granules towards the lumen
Paneth cellCrypt baseClusteredGroups of cells at the very base of crypts
Neuroendocrine cellBasal, fineInfranuclearSmall orange-red granules towards the basement membrane
Neuroendocrine cellScatteredSingle cellsIsolated cells along the crypt, often with a pale halo
Memory hook: Paneth granules point up to the lumen (they fight microbes there); neuroendocrine granules point down to the blood vessels (they release hormones there).
Side-by-Side Comparison
Paneth cells vs neuroendocrine cells
| Feature | Paneth cells | Neuroendocrine cells |
|---|---|---|
| Position in crypt | Crypt base, in clusters | Scattered along the crypt, single cells |
| Granules | Coarse, bright eosinophilic, refractile | Fine, small, eosinophilic to orange |
| Granule location | Apical (supranuclear) | Basal (infranuclear) |
| Products | Lysozyme, alpha-defensins, other antimicrobials | Serotonin, somatostatin, GLP-1, PYY and others |
| Immunostains | Lysozyme, defensin 5 | Chromogranin A, synaptophysin, INSM1 |
| Normal sites | Small bowel, caecum, ascending colon | Entire GI tract |
| Abnormal finding | Left colon or stomach (metaplasia) | Hyperplasia, micronests, neuroendocrine tumour |
Where They Are Normal
Normal distribution along the gut
| Site | Paneth cells | Neuroendocrine cells |
|---|---|---|
| Duodenum to ileum | Normal; most numerous in the ileum | Normal |
| Caecum and ascending colon | Normal | Normal |
| Transverse colon | Proximal part may have a few; beyond that, metaplasia | Normal |
| Descending, sigmoid colon and rectum | Absent normally; presence = metaplasia | Normal |
| Stomach | Absent normally; seen in intestinal metaplasia | Normal (G, D and ECL cells) |
What They Mean in a Biopsy
- Paneth cell metaplasia (left colon) is a marker of chronic mucosal injury, together with crypt distortion and basal plasmacytosis.
- It does not separate ulcerative colitis from Crohn’s disease. It also occurs in chronic infections, diverticular disease and after radiation.
- Absence does not exclude chronicity: look for the other architectural features.
- Neuroendocrine cell hyperplasia and small micronests occur in chronic colitis and around chronic injury; they are reactive.
- Neuroendocrine tumours form a mass with nests or trabeculae and a stromal reaction; a few extra endocrine cells within crypts are not a tumour.
Stains That Help
When H&E is not enough
| Stain | Paneth cells | Neuroendocrine cells |
|---|---|---|
| Chromogranin A, synaptophysin, INSM1 | Negative | Positive |
| Lysozyme, defensin 5 | Positive | Negative |
| Phloxine-tartrazine | Granules bright red | Not highlighted |
| Grimelius (argyrophil) | Negative | Positive |
In practice, immunostains are rarely needed. Granule size and position on H&E settle most cases.
Test Yourself: 10 MCQs
Paneth vs neuroendocrine cells: 10 MCQs
Morphology, distribution, metaplasia and stains, with instant explanations.
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More practice: the GI pathology MCQ bank →
Exam Pearls
- Paneth granules: coarse, apical. Neuroendocrine granules: fine, basal.
- Paneth cells are normal in the right colon; distal to the hepatic flexure they are metaplastic.
- Paneth cell metaplasia means chronicity, not a specific diagnosis.
- Chromogranin and synaptophysin mark neuroendocrine cells; lysozyme marks Paneth cells.
- Paneth cells in the stomach point to intestinal metaplasia.
Video lesson
Paneth vs neuroendocrine cells, explained
A short video on telling the two apart in a colonic biopsy.
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References
- Odze RD, Goldblum JR. Odze and Goldblum Surgical Pathology of the GI Tract, Liver, Biliary Tract and Pancreas. 4th ed. Elsevier; 2023.
- Feakins RM. Inflammatory bowel disease biopsies: updated British Society of Gastroenterology reporting guidelines. J Clin Pathol. 2013;66:1005–1026.
- Young B, O’Dowd G, Woodford P. Wheater’s Functional Histology. 6th ed. Elsevier; 2014.
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