Three point checklist
The three-point checklist was initially developed for non-experts as a skin cancer screening tool. The three-point checklist has a high sensitivity for pigmented skin cancers, including pigmented BCC and melanoma 2,6 This checklist includes three dermoscopic features, including:
- Asymmetry of pattern and structures, defined as asymmetry in the distribution of dermoscopic color and/or structures in one or two perpendicular axes. The contour or silhouette of the lesion does not factor into whether the lesion is symmetric or not.
- Blue-white structures, defined as blue-white veil and/or white scar-like depigmentation and/or blue pepper-like granules.
- Atypical network, defined as Pigment network with thick lines and irregular holes.
The presence of more than one of these criteria is suggestive for melanoma (Fig. 1, 2, 3, 4)
In 2004 Soyer et al. demonstrated that the three-point checklist had a diagnostic value in screening procedure also when used by non expert. In their study, six non-experienced dermoscopists after a 1-hour introduction to the three-point checklist were asked to evaluate 231 clinically suspicious lesions using this algorithm. Finally, the non-experts were able to identify malignant pigmented skin lesions with a sensitivity of 96% and a specificity of 33%.
The pilot study was followed in 2006 by a larger one performed by Zalaudek et al. in order to revalue the preliminary results. The study was open both to experts and non-experts in dermoscopy who, after a short web-based dermoscopy training, evaluated dermoscopy images of 165 skin lesions following the aforementioned algorithm. The results showed good inter-observer reproducibility with a kappa value of 0.53, sensitivity of 91% (not influenced by the observers’ experience) and an overall specificity of 72% for malignancy (significantly influenced by observers’ skills). The best predictor of malignancy was asymmetry followed by the blue-white structures and atypical network.
In order to improve skin cancer screening and educational campaigns, one of us in 2006 tested in a prospective study if the adjunct of dermoscopy to the standard clinical examination of primary care physicians (PCPs) could improve the accuracy of skin cancer triage. After 1-day training course on dermoscopy, PCPs in Naples and in Barcelona were randomly assigned to the dermoscopy evaluation arm or naked-eye evaluation arm. During a 16-month period, 73 PCPs evaluated 2522 skin lesions in their clinics and scored them following the three-point checklist criteria. All patients were revalued by expert dermoscopists.
Sensitivity, specificity, positivity and negative predictive values were calculated for both arms. Significant differences were found in term of sensitivity and negative predictive value (p=0.002 in the naked-eye evaluation arm; p=0,004 in the dermoscopy evaluation arm). In conclusion dermoscopic criteria had shown to improve the ability of PCPs in skin cancer triage and to reduce useless expert consultation. However, further studies are necessary to define new dermoscopic algorithm allowing to easily distinguish also non-pigmented skin lesions such as amelanotic melanoma and non-pigmented BCC.
- Soyer et al.: Three-point checklist of dermoscopy. A new screening method for early detection of melanoma. Dermatology (Basel) 2004;208:27-31. PMID: 14730233. DOI.
- Zalaudek et al.: Three-point checklist of dermoscopy: an open internet study. Br. J. Dermatol. 2006;154:431-7. PMID: 16445771. DOI.
- Argenziano et al.: Dermoscopy improves accuracy of primary care physicians to triage lesions suggestive of skin cancer. J. Clin. Oncol. 2006;24:1877-82. PMID: 16622262. DOI.