Three point checklist

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 Authored by: Teresa Russo     ·  Giuseppe Argenziano

 Keywords:   three-point · checklist · malignant · melanoma · pigmented basal cell carcinoma · benign
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Author(s) Teresa Russo · Giuseppe Argenziano
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Status update September 11, 2017
Status by Ralph P. Braun
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In 2003, during the Virtual Consensus Net Meeting on DermoscopyDermoscopy is a non invasive diagnostic method. (CNMD) a simple algorithmIn mathematics and computer science, an algorithm (Listeni/ˈælɡərɪðəm/ AL-gə-ri-dhəm) is a self-contained sequence of actions to be performed. Algorithms can perform calculation, data processing and automated reasoning tasks., called three-pointThis glossary term has not yet been described. checklistThis glossary term has not yet been described., was established to distinguish malignantThis glossary term has not yet been described. [i.e. melanomaThis glossary term has not yet been described. and pigmented basal cell carcinomaThis glossary term has not yet been described. (BCC)] from benignThis glossary term has not yet been described. pigmented skin lesions[1][2].

The algorithm relies on the following criteriaThis glossary term has not yet been described.

  1. Asymmetry in structure and/or in colorColor (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or blue. in one or two axis of the lesion. The contour shape of the lesion does not impact on the symmetry.
  2. Atypical networkNetwork with increased variability in the color, thickness, and spacing of the lines of the network; asymmetrically distributed; gray color, defined as pigmented network with thickened lines and irregular distribution.
  3. Blue-white structures, namely any white and/or blue color visible in the lesion, including blue-white veil, scar-like depigmentationArea of white that is whiter than surrounding normal skin (true scarring). It should not be confused with hypo- or depigmentation due to simple loss of melanin. Shiny white structures and blood vessels are not seen in areas of regression., and regressionThis glossary term has not yet been described. structures such as peppering.

The presence of more than one of these criteria is suggestive for melanoma (Fig. 1, 2, 3, 4)


Figure 1: Three point checklist
Figure 1: Three pointThis glossary term has not yet been described. checklist


Figure 2: Melanoma showing asymmetry in color and structure, blue-white structures and atypical network (score 3: malignant lesion)
Figure 2: MelanomaThis glossary term has not yet been described. showing asymmetry in color and structure, blue-white structures and atypical networkNetwork with increased variability in the color, thickness, and spacing of the lines of the network; asymmetrically distributed; gray color (score 3: malignant lesion)


Figure 3: Dermoscopy of a nevus exhibiting only blue structures (score 1: benign lesion)
Figure 3: Dermoscopy of a nevus exhibiting only blue structures (score 1: benign lesion)


Figure 4: A basal cell carcinoma characterized by asymmetry and blue structures (score 2: suspicious lesion)
Figure 4: A basal cell carcinomais the most common skin cancer, and one of the most common cancers in the United States.[1] While BCC has a very low metastatic risk, this tumor can cause significant disfigurement by invading surrounding tissues characterized by asymmetry and blue structures (score 2: suspicious lesion)

In 2004 Soyer et al.[3] 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.[4] in order to revalue the preliminary results. The study was open both to experts and non-experts in dermoscopyDermoscopy is a non invasive diagnostic method. 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[5] 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-pigmentedThis glossary term has not yet been described. skin lesions such as amelanotic melanomatype of skin cancer in which the cells do not make melanin and non-pigmented BCC.



References
  1. Argenziano & Soyer: Dermoscopy of pigmented skin lesions--a valuable tool for early diagnosis of melanoma. Lancet Oncol. 2001;2:443-9. PMID: 11905739.
  2. Argenziano et al.: Dermoscopy of pigmented skin lesions: results of a consensus meeting via the Internet. J. Am. Acad. Dermatol. 2003;48:679-93. PMID: 12734496. DOI.
  3. 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.
  4. Zalaudek et al.: Three-point checklist of dermoscopy: an open internet study. Br. J. Dermatol. 2006;154:431-7. PMID: 16445771. DOI.
  5. 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.