Diagnostic Features of Cutaneous Micromelanoma (≤ 6 mm): A Systematic Review and Meta‐Analysis

The ABCD(E) criteria implied that melanoma below 6 mm was rare, and dermoscopic criteria were derived from clinically evident tumors. We aimed to pool clinical, dermoscopic, and reflectance confocal microscopy features of melanoma ≤ 6 mm (micromelanoma) and evaluate the diagnostic performance of established algorithms. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, five databases were searched from inception to June 2026. Two reviewers performed selection, extraction, and Joanna Briggs Institute risk-of-bias assessment. Proportions, odds ratios (OR), and accuracy were pooled with random-effects models. This study was registered in PROSPERO (CRD420251133150). Twenty-four studies (1017 micromelanomas, 2604 comparators) were included. Overall, 40.0% (95% confidence interval [CI] 30.0-51.0) of micromelanomas were invasive, with a mean Breslow thickness of 0.46 mm (95% CI 0.37-0.56) among invasive tumors. Structural asymmetry (58.7%, 95% CI 40.4-74.8) and irregular dots or globules (57.9%, 95% CI 40.0-74.0) were among the most prevalent dermoscopic features. Irregular pigmentation (OR 23.37, 95% CI 5.37-101.79) and atypical vessels (OR 12.52, 95% CI 3.18-49.39) had the largest ORs versus size-matched nevi. A starburst pattern was tenfold more common than in larger melanoma (OR 10.16, 95% CI 4.42-23.32) yet did not separate micromelanoma from nevi (OR 1.67, 95% CI 0.81-3.43). The ABCDE rule was least sensitive (47.1%, 95% CI 34.1-60.5). Limitations included very low certainty of evidence, high heterogeneity, and variable size cut-offs. Small diameter does not preclude invasion. In exploratory comparisons, established algorithms underperformed in lesions ≤ 6 mm. High-specificity dermoscopic clues may raise suspicion and support biopsy, even without a positive algorithm score.