The problem of false-positive diagnosis in melanoma screening

Abstract

The predictive value of melanoma diagnosis made by visual examination during pigmented lesion screening is low. This creates the problem of false-positive diagnoses, which lead to unnecessary treatment and scarring. The purpose of this study was to evaluate the impact of dermoscopy (epiluminescence microscopy, dermatoscopy) on the false-positive rate in the routine melanoma screening activity of a pigmented lesion clinic (PLC). In a series of 133 subjects consecutively referred to the PLC, lesions defined as suspicious or equivocal on visual examination were examined by dermoscopy. Only lesions also defined as suspicious on dermoscopy were excised; other lesions were observed at follow-up examinations. Among the 2542 pigmented lesions observed, clinical examination led to identification of 43 suspicious lesions, 13 of which were also suspicious on dermoscopy and were subsequently excised. Histopathological examination revealed three malignant melanomas. Compared with visual examination alone, the addition of dermoscopy to the subgroup of clinically equivocal lesions resulted in an increase in specificity from 98.4% to 99.6% and in positive predictive value from 6.9% to 23%. The specificity of the visit outcome 'subject to be referred for surgical excision' increased from 69.2% to 92.3%. No false-negative melanoma diagnoses on dermoscopy were observed during a follow-up period of 4 years. The addition of dermoscopy to routine PLC activity as a second-level examination led to a reduction in the number of false-positive diagnoses, thus producing an overall increase in the specificity and positive predictive value of melanoma diagnosis.

Impact of Dermoscopy on the Management of High-risk Patients From Melanoma Families: A Prospective Study

“…Dermoscopy reduced the number of excisions considerably (42%), which is in agreement with other studies (7)(8)(9). In a randomized study Carli et al (7) found that 38% less excisions were performed in the dermoscopy study-arm compared with the NEE arm.…”

“…Several studies have shown that dermoscopy is better than naked eye examination (NEE) at discriminating melanoma from benign pigmented lesions (4)(5)(6). However, few studies have investigated the effect of dermoscopy in everyday clinical practice by studying how it guides management decisions (7)(8)(9)(10). The beneficial effect of dermoscopy ultimately depends on how it improves the ability to determine whether lesions need to undergo biopsy (8,(11)(12)(13)(14).…”

Malignant Melanoma S3‐Guideline “Diagnosis, Therapy and Follow‐up of Melanoma”

“…From a meta-analysis of nine level II diagnostic studies subject to varying degrees of verification bias performed prospectively in a clinical setting the diagnostic accuracy for melanoma, as expressed by the relative diagnostic odds ratio, was 15.6 (95 % CI 2.9-83.7) times higher for dermoscopy compared with naked eye examination [26][27][28][29][30][31][32][33][34][35][36]." ([19] p. 29).…”

“…For this reason, and based on other evidence [39], some formal training in dermoscopy is required to achieve improvement in diagnostic accuracy." ([19], p. [29][30].…”

Statistical Significance and Clinical Relevance

“…10 However, to show that dermoscopy is more sensitive than clinical examination in detecting melanomas is problematic. The sensitivity of a dermatologist in detecting a melanoma is very high.…”