Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Jul 31;2(3):203a08.
doi: 10.5826/dpc.0203a08. Print 2012 Jul.

Accuracy of the first step of the dermatoscopic 2-step algorithm for pigmented skin lesions

Philipp Tschandl  1 , Cliff Rosendahl, Harald Kittler
Affiliations

Accuracy of the first step of the dermatoscopic 2-step algorithm for pigmented skin lesions

Philipp Tschandl et al. Dermatol Pract Concept. .

Abstract

Objectives: To evaluate the frequency of misclassifications of equivocal pigmented lesions according to the first step of the dermatoscopic 2-step algorithm.

Patients and methods: 707 consecutive cases from 553 patients of central Europe and Australia were included in the study. Dermatoscopic images were evaluated in a blinded fashion for the presence of features described in the 2-step algorithm to determine their melanocytic or non-melanocytic origin. Mucosal, genital and non-pigmented lesions were excluded.

Results: The sensitivity of the first step was 97.1% for patients from Australia and 96.8% for patients from central Europe. The specificity was 33.6% for Australian patients and 67.9% for European patients. The most common reasons for misclassification were the presence of a pigmented network in a non-melanocytic lesion (n=68, 25.2%) and the absence of dermatoscopic features of melanocytic and non-melanocytic lesions in 69 (25.6%) non-melanocytic lesions.

Conclusion: The first step of the dermatoscopic 2-step algorithm, if applied consistently, has high sensitivity but low specificity. Many non-melanocytic lesions, especially solar lentigines and seborrheic keratoses, are wrongly classified as melanocytic. The worse performance of the first step algorithm in Australian patients is probably due to a higher rate of solar lentigines in patients with severely sun-damaged skin.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Distribution of lesions regarding body site and geographic origin. Given frequencies are calculated within each geographic group. [Copyright: ©2012 Tschandl et al.]
Figure 2
Figure 2
Pigmented network leading to a wrong classification. (A) Seborrheic keratosis. (B) Solar lentigo. (C) Seborrheic keratosis. (D) Solar lentigo. [Copyright: ©2012 Tschandl et al.]
Figure 2
Figure 2
Pigmented network leading to a wrong classification. (A) Seborrheic keratosis. (B) Solar lentigo. (C) Seborrheic keratosis. (D) Solar lentigo. [Copyright: ©2012 Tschandl et al.]
Figure 2
Figure 2
Pigmented network leading to a wrong classification. (A) Seborrheic keratosis. (B) Solar lentigo. (C) Seborrheic keratosis. (D) Solar lentigo. [Copyright: ©2012 Tschandl et al.]
Figure 2
Figure 2
Pigmented network leading to a wrong classification. (A) Seborrheic keratosis. (B) Solar lentigo. (C) Seborrheic keratosis. (D) Solar lentigo. [Copyright: ©2012 Tschandl et al.]
Figure 3
Figure 3
An absence of any specific melanocytic or non-melanocytic (“melanocytic by default”) features, leading to a wrong classification. (A & B) Pigmented Bowen’s disease. (C & D) Seborrheic keratosis. [Copyright: ©2012 Tschandl et al.]
Figure 3
Figure 3
An absence of any specific melanocytic or non-melanocytic (“melanocytic by default”) features, leading to a wrong classification. (A & B) Pigmented Bowen’s disease. (C & D) Seborrheic keratosis. [Copyright: ©2012 Tschandl et al.]
Figure 3
Figure 3
An absence of any specific melanocytic or non-melanocytic (“melanocytic by default”) features, leading to a wrong classification. (A & B) Pigmented Bowen’s disease. (C & D) Seborrheic keratosis. [Copyright: ©2012 Tschandl et al.]
Figure 3
Figure 3
An absence of any specific melanocytic or non-melanocytic (“melanocytic by default”) features, leading to a wrong classification. (A & B) Pigmented Bowen’s disease. (C & D) Seborrheic keratosis. [Copyright: ©2012 Tschandl et al.]
Figure 4
Figure 4
Difference between 2-step algorithm (A) versus “chaos and clues” algorithm (B). [Copyright: ©2012 Tschandl et al.]
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Kittler H, Pehamberger H, Wolff K, Binder M. Diagnostic accuracy of dermoscopy. Lancet Oncol. 2002;3(3):159–65. - PubMed
    1. Vestergaard ME, Macaskill P, Holt PE, Menzies SW. Dermoscopy compared with naked eye examination for the diagnosis of primary melanoma: a meta-analysis of studies performed in a clinical setting. Br J Dermatol. 2008;159(3):669–76. - PubMed
    1. Rosendahl C, Tschandl P, Cameron A, Kittler H. Diagnostic accuracy of dermatoscopy for melanocytic and nonmelanocytic pigmented lesions. J Am Acad Dermatol. 2011;64(6):1068–73. - PubMed
    1. Argenziano G, Fabbrocini G, Carli P, De Giorgi V, Sammarco E, Delfino M. Epiluminescence microscopy for the diagnosis of doubtful melanocytic skin lesions. Comparison of the ABCD rule of dermatoscopy and a new 7-point checklist based on pattern analysis. Arch Dermatol. 1998;134(12):1563–70. - PubMed
    1. Henning JS, Dusza SW, Wang SQ, et al. The CASH (color, architecture, symmetry, and homogeneity) algorithm for dermoscopy. J Am Acad Dermatol. 2007;56(1):45–52. - PubMed

LinkOut - more resources