Background: While dermatoscopy’s added value to clinical imaging is known, the standalone value of dermatoscopy and clinical images remains unclear.

Objective: To quantify the standalone and complementary value of dermatoscopy and clinical close-up imaging across lesion types and reader expertise.

Methods: In an online reader study, 283 participants diagnosed 1,567 paired images (clinical close-up/dermatoscopic) of skin cancers and mimics. The presentation order was randomized. Diagnostic accuracy, sensitivity, and specificity were compared. The effects of modality, reader expertise, and presentation order were analysed using a generalized linear mixed model.

Results: Dermatoscopy alone showed higher sensitivity (85.0% vs. 74.2%) but lower specificity (66.8% vs. 71.9%) compared with clinical close-up images alone. It improved accuracy for melanoma and basal cell carcinoma, but not for nevi. Adding either modality increased the odds of a correct diagnosis. Dermatoscopy raised the odds by 52% (OR=1.52; 95%CI:1.36-1.70;p<0.001), while clinical close-ups increased the odds by 40% (OR=1.40;95%CI:1.20-1.61;p<0.001).

Limitations: Image-based evaluation simulated teledermatology rather than face-to-face assessment; potential selection and verification bias cannot be excluded.

Conclusion: Dermatoscopy alone yields higher sensitivity for malignant lesions but lower specificity for nevi than clinical close-up images. The latter provides complementary diagnostic cues, underscoring the value of integrating both modalities for optimal assessment.