Cross-Polarized Macro Photography versus Polarized Dermoscopy in Basal Cell Carcinoma: A Blinded Paired-Image Comparison.

Abstract

Background: Polarized dermoscopy (PD) is the established non-contact imaging modality for basal cell carcinoma (BCC). Cross-polarized macro photography (CPMP) applies analogous optical principles using widely available equipment, but its performance relative to PD has not been systematically evaluated.

Objective: To compare dermoscopic feature visibility, image quality, and expert modality preference between CPMP and PD in BCC using a blinded, paired-image design.

Methods: One hundred paired CPMP and PD images of histopathologically confirmed BCCs, acquired during the same clinical visit, were digitally masked to remove modality-revealing cues and reviewed in randomized side-by-side pairs. Feature visibility was assessed by three dermoscopists; image quality by a multidisciplinary panel using the DIQS-5 (a structured 5-point dermoscopic image quality scale); and modality preference by three dermatologists with varying CPMP familiarity across two blinded rounds with a washout period.

Results: Feature visibility did not differ significantly for any established BCC criterion (all P > 0.05). CPMP scored significantly higher for depth of field and color fidelity (both P < 0.001); sharpness was comparable between modalities (P = 0.494). CPMP captured all lesions ≥1 cm in a single frame, whereas 41.5% of large lesions exceeded PD's field of view. The majority of raters preferred CPMP in both evaluation rounds, with phenotype-dependent patterns: CPMP was favored for pigment-rich lesions and PD for lesions with fine vascular structures.

Conclusion: CPMP demonstrated feature visibility comparable to PD while offering measurable advantages in depth of field, field of view, and color rendering, suggesting complementary roles for these modalities in BCC imaging.