Melanoma Detection in Pigmented Lesions ≤ 6 mm Selected for Excision After Dermoscopy in Routine Practice: A Retrospective Cross-Sectional Study

Background: Dermoscopy has increased the excision of very small pigmented lesions in routine practice, yet the diagnostic efficiency of excising lesions ≤ 6 mm judged suspicious for melanoma remains incompletely defined. Objectives: The objectives of this study were to quantify melanoma detection yield and number needed to excise (NNE) for pigmented lesions ≤ 6 mm excised after clinical and dermoscopic suspicion of melanoma and to describe melanoma characteristics according to lesion diameter. Methods: We performed a retrospective observational cross-sectional study at a tertiary dermatologic oncology referral center within the Tuscany Regional Health Service, Florence, Italy. All pigmented lesions excised between 1 January 2022 and 31 December 2023 were screened. Consecutive lesions were included if they were excised because melanoma or suspected melanoma was the preoperative clinicodermoscopic diagnosis; lesions removed for benign or cosmetic indications were excluded. Primary outcomes were melanoma yield and number needed to excise, overall and stratified by clinical diameter. Multivariable logistic regression was performed to assess whether lesion diameter was independently associated with melanoma diagnosis after adjustment for age, sex, and anatomical site. Results: Among 2240 included excisions, 609 melanomas were diagnosed, corresponding to an overall yield of 27.2%. Lesions ≤ 6 mm accounted for 1331 excisions and yielded 175 melanomas, with a yield of 13.1% and a number needed to excise of 7.6. Lesions > 6 mm accounted for 909 excisions and yielded 434 melanomas, with a yield of 47.7% and a number needed to excise of 2.1. Thus, 86.9% of excised lesions ≤ 6 mm were benign on histopathology. Melanomas diagnosed in lesions ≤ 6 mm showed a more favorable histopathologic profile than larger melanomas. In multivariable analysis, lesions > 6 mm had significantly higher odds of melanoma than lesions ≤ 6 mm after adjustment for age, sex, and anatomical site (adjusted odds ratio 4.77, 95% confidence interval 3.81–5.97; p < 0.001). Conclusions: In routine practice, excision of dermoscopically suspicious pigmented lesions ≤ 6 mm has markedly lower melanoma yield and higher NNE than excision of larger lesions. These findings support risk-stratified management approaches and careful consideration of excision thresholds for very small lesions.