Weighted 7-Point Checklist for Pigmented Lesions
Weighted 7-Point Checklist for Pigmented Lesions
Three major features at 2 points, four minor at 1 point. NICE names a score of 3 or more in its skin cancer recommendations — and in the validation cohort the specificity at that cut-off was 35 per cent and three of 36 melanomas scored below it.
Weighted 7-point checklist
7 items → 0–10Change in size (2); irregular pigmentation (2); regular border (0); no inflammation (0); itch (1); diameter under 7 mm (0); no oozing (0)
Scoring
Change in size of the lesion · Irregular pigmentation · Irregular border
Minor features, 1 point each
Inflammation · Itch or altered sensation · Larger than other lesions (diameter over 7 mm) · Oozing or crusting
Total 0–10. NICE names a score of 3 or more.
- weighted, not the original
- the original 7-point checklist from Glasgow scored all seven features equally. The WEIGHTED version gives the three major features 2 points each, and it is the version NICE names. In the validation cohort the two performed differently at the same cut-off of 3: the weighted checklist reached 80.9 per cent sensitivity for a clinically significant lesion against the original’s 62.7 per cent, and paid for it in specificity — 35.0 per cent against 65.0
- three ways to reach 3
- one major and one minor, two majors, or three minors. One major feature alone scores 2 and does not reach it; two minor features score 2 and do not either. That structure is worth knowing because it means three soft symptoms — itch, a 9 mm diameter and a little crust — reach the threshold without any change in the lesion’s appearance
- sensitive, not specific
- sensitivity 80.9 per cent and specificity 35.0 per cent for a clinically significant lesion at the recommended cut-off, in 1,436 lesions from 1,182 patients in UK general practice. Positive predictive value 18.8 per cent, negative predictive value 90.8 per cent. For melanoma alone, sensitivity 91.7 per cent and specificity 33.1 per cent
- what a low score does NOT do
- it does not exclude melanoma. At 91.7 per cent melanoma sensitivity, three of that cohort’s 36 melanomas scored below 3. NICE’s separate dermoscopy recommendation applies whatever this total is, and the clinician’s own concern about a lesion is not overridden by a checklist
- the cut-off of 4 the study proposed
- the same cohort showed that moving the threshold from 3 to 4 raised specificity for clinically significant lesions from 35.0 to 57.1 per cent and lowered sensitivity from 80.9 to 73.3 per cent, while MELANOMA sensitivity was unchanged at 91.7 per cent. That is the authors’ finding; the recommended threshold remains 3
- what it is not for
- it is a checklist for a PIGMENTED lesion in primary care. It says nothing about basal cell or squamous cell carcinoma, nothing about an amelanotic melanoma, and nothing about a subungual or acral lesion, where the features it asks about behave differently. Once a melanoma is diagnosed, the measurement that matters is the Breslow thickness
Worked example
Change in size (2); irregular pigmentation (2); regular border (0); no inflammation (0); itch (1); diameter under 7 mm (0); no oozing (0)
2 + 2 + 0 + 0 + 1 + 0 + 0 = 5 points
That is at or above the score of 3 or more that NICE names in its skin cancer recommendations
Take away the itch and the total is 4 — still at or above it. Take away the irregular pigmentation as well and it is 2, below it, on a lesion that is still changing in size
Now the other direction: itch, a 9 mm diameter and a little crust, with no change in size, no irregular pigment and a regular border, also scores 3. Three minor features reach the same threshold as two major ones
In the validation cohort a score of 3 or more had a positive predictive value of 18.8 per cent for a clinically significant lesion — roughly four in five lesions at or above the threshold were benign — and a score below 3 still missed three of 36 melanomas
Neither of those facts is a decision. This page computes the total and names the guideline; the clinician decides, and NICE's dermoscopy recommendation applies whatever the total
The seven features and their weights
| Feature | Weight | Note |
|---|---|---|
| Change in size of the lesion | 2 (major) | Change over weeks to months in a previously stable lesion |
| Irregular pigmentation | 2 (major) | Variation in colour within the lesion, not simply a dark lesion |
| Irregular border | 2 (major) | Notched, scalloped or indistinct outline |
| Inflammation | 1 (minor) | Not explained by recent trauma |
| Itch or altered sensation | 1 (minor) | One of the two most commonly reported items in the validation cohort |
| Larger than other lesions, over 7 mm | 1 (minor) | Both a size threshold and a comparison with the patient’s own naevi |
| Oozing or crusting | 1 (minor) | Serous crust or bleeding without obvious injury |
Performance at both cut-offs, in one UK primary care cohort
| Cut-off | Target | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|
| 3 or more (recommended) | Clinically significant lesion | 80.9% (75.1–85.8) | 35.0% (32.3–37.8) | 18.8% | 90.8% |
| 3 or more (recommended) | Melanoma | 91.7% (77.5–98.3) | 33.1% (30.7–35.7) | not reported | not reported |
| 4 or more (proposed) | Clinically significant lesion | 73.3% | 57.1% | 24.1% | 92.0% |
| 4 or more (proposed) | Melanoma | 91.7% | 53.4% | not reported | not reported |
| Original unweighted checklist, 3 or more | Clinically significant lesion | 62.7% | 65.0% | not reported | not reported |
A deliberately sensitive instrument, and what that costs
The 7-point checklist came out of Glasgow and exists to help a clinician who sees a pigmented lesion decide whether it needs specialist assessment. The weighted version — three major features at 2 points, four minor at 1 — is the one NICE names in its skin cancer recommendations, at a score of 3 or more. The structure means the threshold can be reached three ways: one major feature and one minor, two majors, or three minors. Three soft symptoms with an entirely ordinary-looking lesion will reach it, and a single major feature on its own will not.
What the instrument is, and is not, good at is quantified. A diagnostic validation study assessed 1,436 pigmented lesions from 1,182 patients in general practices in eastern England, among which were 225 clinically significant lesions and 36 melanomas. At the recommended cut-off of 3 or more, the weighted checklist had a sensitivity of 80.9 per cent and a specificity of 35.0 per cent for a clinically significant lesion, with a positive predictive value of 18.8 per cent. For melanoma specifically sensitivity was 91.7 per cent. Those numbers describe an instrument designed to catch rather than to discriminate: roughly four in five lesions that reached the threshold were benign, and roughly one melanoma in twelve did not reach it.
That last figure is the one to hold on to. A low score does not exclude malignancy. Three of this cohort’s 36 melanomas scored below 3, and NICE carries a separate recommendation that does not depend on this score at all — to refer using a suspected cancer pathway referral if dermoscopy suggests melanoma. A low total is a low total; it does not make a lesion benign, and it does not override a clinician’s or a patient’s concern about a changing mole. The same study found that moving the cut-off from 3 to 4 would have raised specificity from 35.0 to 57.1 per cent with no loss of melanoma sensitivity in that cohort — an interesting finding about one dataset, not a change to the recommended threshold.
The checklist has a narrow scope. It is for pigmented lesions and says nothing about basal cell or squamous cell carcinoma, nothing about an amelanotic melanoma, and nothing about acral or subungual sites where its features behave differently. A score is not a diagnosis, and a number from a derivation cohort is not a probability for the patient in front of you. Once a melanoma is diagnosed, the measurement that drives everything after it is the Breslow thickness, whose AJCC thresholds moved in the eighth edition; the laboratory markers that accompany follow-up are the S100B unit converter and the LDH unit converter. This page computes the published number and names the guideline or trial that defines its thresholds. It renders no clinical decision.
Frequently asked questions
What is the weighted 7-point checklist score?
Three major features — change in size, irregular pigmentation, irregular border — score 2 points each, and four minor features — inflammation, itch or altered sensation, diameter over 7 mm, oozing or crusting — score 1 each. The total runs 0 to 10. NICE names a score of 3 or more in its skin cancer recommendations.
How accurate is the weighted 7-point checklist?
In 1,436 pigmented lesions from 1,182 UK general practice patients, a score of 3 or more had a sensitivity of 80.9 per cent and a specificity of 35.0 per cent for a clinically significant lesion, with a positive predictive value of 18.8 per cent. For melanoma alone, sensitivity was 91.7 per cent and specificity 33.1 per cent.
Does a score below 3 mean the lesion is benign?
No. A low score does not exclude malignancy. In the validation cohort three of 36 melanomas scored below 3, and NICE carries a separate recommendation — to refer if dermoscopy suggests melanoma — that applies whatever this total is. The checklist supports a clinician’s assessment and does not replace it.
What is the difference between the original and the weighted checklist?
The original Glasgow checklist scored all seven features equally; the weighted version gives the three major features 2 points each. In the same validation cohort at a cut-off of 3, the weighted version was more sensitive (80.9 against 62.7 per cent for clinically significant lesions) and much less specific (35.0 against 65.0 per cent).
Should the cut-off be 3 or 4?
NICE names 3 or more. The validation study noted that a cut-off of 4 would have raised specificity from 35.0 to 57.1 per cent for clinically significant lesions while melanoma sensitivity stayed at 91.7 per cent in that cohort. That is a finding about one dataset and is reported here as such; this page names the recommended threshold and makes no recommendation of its own.
Related calculators
References
- Walter FM, Prevost AT, Vasconcelos J, et al. Using the 7-point checklist as a diagnostic aid for pigmented skin lesions in general practice: a diagnostic validation study. Br J Gen Pract. 2013;63(610):e345–53. 1,436 lesions in 1,182 patients, 36 melanomas.
- National Institute for Health and Care Excellence. Suspected cancer: recognition and referral, NG12, skin cancer recommendations — the weighted 7-point checklist score of 3 or more, and the separate dermoscopy recommendation. nice.org.uk/guidance/ng12
- Gershenwald JE, Scolyer RA, Hess KR, et al. Melanoma staging: evidence-based changes in the American Joint Committee on Cancer eighth edition cancer staging manual. CA Cancer J Clin. 2017;67(6):472–92. Read as the open-access author manuscript.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/