Diagnostic accuracy of dermoscopy for 934 basal cell carcinomas: A single‐center retrospective study

Although the efficacy of dermoscopic diagnosis of basal cell carcinoma (BCC) has already been established, most studies have been conducted in Western countries. However, there are racial differences in the clinicopathological characteristics of BCC, highlighting the need for a survey among Asians. Herein, we aimed to investigate the diagnostic accuracy of dermoscopy in 934 Japanese patients with BCC and statistically analyze the clinicopathological factors affecting diagnostic accuracy. We analyzed 5093 skin lesions, including 934 BCCs that were diagnosed consecutively from 1998 to 2018. The sensitivity and specificity of dermoscopic diagnosis for BCC were calculated. The sensitivity and specificity of dermoscopic diagnosis were 92.2% and 96.0%, respectively. There were 73 false-negative cases of BCCs that were clinically diagnosed with other diseases. The most common incorrect clinical diagnosis was seborrheic keratosis (n = 18), followed by melanocytic nevus (n = 15). Multiple logistic regression analysis showed that sensitivity was significantly lower in BCCs located on the trunk and extremities, which showed low pigmentation (less than 10% of the lesion surface) and were diagnosed by a resident dermatologist. Experience of 3-6 months of 12 resident dermatologists revealed increased sensitivity. Dermoscopy is a reliable tool for the accurate diagnosis of BCC in Japanese individuals. Care should be taken when diagnosing BCCs of the trunk and extremities, and the less-pigmented subtype because of lower sensitivity. A certain amount of experience is required to improve the skills for dermoscopy.