Objective To summarize the dermoscopic features of superficial basal cell carcinoma (BCC) and Bowen's disease and explore the diagnostic value of dermoscopy for these two conditions.

Methods A retrospective analysis was conducted on the clinical and dermoscopic features of patients with histopathologically confirmed superficial BCC and Bowen's disease at Peking Union Medical College Hospital from September 2021 to September 2023. Intergroup comparisons were performed. Using histopathology as the gold standard, the diagnostic accuracy of clinical visual assessment and dermoscopy-assisted diagnosis for superficial BCC and Bowen's disease was calculated.

Results A total of 29 patients with superficial BCC and 64 patients with Bowen's disease met the inclusion and exclusion criteria. Among them, 20 superficial BCC patients and 23 Bowen's disease patients underwent dermoscopic examination. The mean ages of the superficial BCC and Bowen's disease groups were (67.5±13.3) years and (69.9±10.9) years, respectively, with male-to-female ratios of 1∶2.22 and 1∶1.13. Except for the proportions of lesions < 1 cm in diameter and brown lesions, which showed statistically significant differences, other clinical features—including lesion location, solitary/multiple lesions, well-defined borders, and presence of ulceration/bleeding—did not differ significantly (all P > 0.05). Common dermoscopic features of superficial BCC included bright white globules or streaks (80.0%), leaf-like areas/spoke-wheel areas/concentric structures (70.0%), and short fine telangiectasia (60.0%). In contrast, Bowen's disease frequently exhibited glomerular vessels (87.0%), yellow scales (78.3%), dotted vessels (69.6%), and homogeneous brown/gray pigmentation (65.2%). Compared with Bowen's disease, superficial BCC showed higher frequencies of bright white globules/streaks (80.0% vs. 43.5%, P=0.015), leaf-like/spoke-wheel/concentric structures (70.0% vs. 0, P < 0.001), short fine telangiectasia (60.0% vs. 26.1%, P=0.025), scattered brown dots (50.0% vs. 13.0%, P=0.008), blue-gray dots/globules (20.0% vs. 0, P=0.024), and blue-gray ovoid nests (35.0% vs. 0, P=0.002), but lower frequencies of dotted vessels (15.0% vs. 69.6%, P < 0.001), glomerular vessels (10.0% vs. 87.0%, P < 0.001), homogeneous brown/gray pigmentation (15.0% vs. 65.2%, P=0.001), and yellow scales (40.0% vs. 78.3%, P=0.010). The clinical visual diagnostic accuracy rates for the 29 superficial BCC patients and 64 Bowen's disease patients were 48.3% and 60.9%, respectively. Among the cases with dermoscopic examination, the clinical visual diagnostic accuracy rates were 30.0% for superficial BCC and 43.5% for Bowen's disease, which improved to 85.0% and 78.3%, respectively, after incorporating dermoscopic features.

Conclusions Superficial BCC and Bowen's disease exhibit distinct dermoscopic features. Dermoscopy significantly improves the diagnostic accuracy for both conditions.