Effect of Lesion Size on the Diagnostic Performance of Dermoscopy in Melanoma Detection

Abstract

Background: Dermoscopy is able to correctly classify a higher number of melanomas than naked-eye examination. Little is known however about factors which may influence the diagnostic performance during practice. The aim of the study was to analyze the effect of size of the lesion on diagnostic performance of dermoscopy in melanoma detection. Methods: Eight dermatologists examined clinical and, separately, clinical and dermoscopic (combined examination) images of 200 melanocytic lesions previously excised [64 melanomas, 24 in situ and 40 invasive (median thickness 0.30 mm) and 136 melanocytic nevi]. After examination, diagnostic performance was analyzed in accordance with the major diameter of the lesions divided into 3 groups, i.e. small (less than 6 mm), intermediate (between 6 and 9 mm) and large (10 mm or more) lesions. These groups were shown to be highly comparable concerning the microstaging of melanomas (median thickness value 0.30, 0.22 and 0.32 mm, respectively). Results: Dermoscopy increased the diagnostic performance of naked-eye examination of both intermediate and large lesions [sensitivity value: +19.3 (p = 0.002) and +10.3 (p = 0.007); diagnostic accuracy value: +7.4 (p = 0.004) and +6.1 (p = 0.07)]. On the contrary, no statistically significant increase was found dealing with small lesions (sensitivity +3.7, p = 0.66; diagnostic accuracy –1.7, p = 0.55). Conclusions: The diagnostic improvement associated with the addition of dermoscopy to naked-eye examination is influenced by the size of the lesion, i.e. it is lacking with lesions up to 6 mm in diameter. The optimized use of dermoscopy in melanoma detection is obtained dealing with melanocytic lesions 6 mm in diameter or larger.

Histopathological diagnosis of small melanocytic lesions suspicious for malignant melanoma

“…5 This seems to be in agreement with the present study, in which only 1 out of 76 suspicious lesions was diagnosed as malignant. Ordinary benign melanocytic lesions usually are not clinically suspicious.…”

“…1,2 However, the diagnostic accuracy of dermoscopy significantly depends on the degree of experience of the examiners and size of lesions. 3-5 Small melanocytic lesions remain a significant diagnostic challenge not only for clinicians and dermoscopists, but also for pathologists because progressive smaller lesions are excised under the screening of dermoscopic features. This study aims to evaluate the range of possible histopathological diagnoses in a group of melanocytic lesions up to 6 mm considered suspicious for MM on clinical and dermoscopical examination.…”

Examination of skin lesions for cancer: Which clinical decision aids and tools are available in general practice?

“…One study even noted a 10% drop in the sensitivity for detecting melanoma when used by untrained dermatologists [73]. Furthermore, it is unclear whether dermoscopy has added value for melanomas smaller than 6 mm [74][75][76].…”

Dermoscopy of Small Basal Cell Carcinoma: Study of 100 Lesions 5 mm or Less in Diameter

“…This study shows that the typical dermoscopic features of BCC are usually present from the beginning of the natural history of this tumor. This is in contrast to what happens in small melanocytic lesions, in which fully represented melanoma‐specific criteria may be difficult to recognize. We found that 77% of small BCCs (≤5 mm diameter) could be diagnosed easily using the Menzies method.…”