- Design
- Interobserver agreement study on scanned slides
- Population
- 7 pathologists grading 58 H&E slides from 20 goblet cell adenocarcinomas
- Primary outcome
- Agreement on WHO 5th edition grade
- Effect
- Fleiss kappa 0.29 (95% CI 0.14 to 0.44); all seven agreed in 4 of 20 cases
Seven pathologists with an interest in appendiceal pathology graded whole-slide images from 20 goblet cell adenocarcinomas (58 H&E slides) using the three-tier WHO 5th edition system. They scored 15 defined histological patterns, plus extracellular mucin.
All seven agreed on the WHO grade in 4 of 20 cases (20%). Fleiss kappa for overall case agreement was 0.29 (95% CI 0.14 to 0.44), which is fair. Pairwise kappa ranged from 0.00 to 0.82. Agreement was best for extracellular mucin (kappa 0.43) and tumour sheets (0.41) and worst for mild architectural disarray or tubular fusion (0.05) and necrosis (0.07).
The set was small, with 20 cases and seven readers, so the estimates are imprecise. The authors suggest a validated two-tier system, low against high grade, may be more reproducible; this was a suggestion, not a result they tested.
- Expect disagreement when grading goblet cell adenocarcinoma under the three-tier WHO system.
- Seek a second opinion from a pathologist with appendiceal experience on borderline grade cases.
- Describe the features you saw and their proportion in the report, not only the grade.
- Tell clinicians that grade carries uncertainty when it drives treatment.
Why it matters
Grade guides decisions about surgery and chemotherapy, so unreliable grading reaches patients.
Don't overread it
Seven readers and 20 cases is a small sample, and it does not show which grading system performs best.
The statistics, in plain English
Kappa corrects agreement for chance: 0 is chance level and 1 is perfect. A value of 0.29 with an interval of 0.14 to 0.44 means agreement was only a little better than chance, even among experts.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for pathology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free