To describe the dermoscopic features of extramammary Paget′s disease (EMPD) and chronic eczema of the vulva, and to explore the value of dermoscopy in the diagnosis and differential diagnosis of the above diseases.

Dermoscopic images were collected from 20 patients with histopathologically confirmed vulvar EMPD and 16 patients with clinically confirmed chronic eczema of the vulva in Hospital for Skin Diseases, Chinese Academy of Medical Sciences and Pekin Union Medical College from January 2017 to April 2018, and retrospectively analyzed. Fisher′s exact test was used to compare the prevalence of dermoscopic features between the two groups.

As dermoscopy showed, the milky red background was observed in 19 EMPD patients and in only 1 patient with chronic eczema, and there was a significant difference in the prevalence of milky red background between the two groups (P < 0.001) . White scales were the most common desquamation, and were observed in 9 EMPD patients and 13 patients with chronic eczema (P = 0.128) . Blood vessels were uniformly distributed in EMPD patients, including dotted-globular vessels in 19 and linear vessels in 14, while blood vessels were distributed in a patchy or clustered pattern in the patients with chronic eczema, including dotted-globular vessels in 16 and linear vessels in 7. There was a significant difference in the prevalence of different distribution patterns of blood vessels between the two groups (P < 0.001) . Bright white streaks, bright white structureless area and reticular structure were observed in 19, 20 and 19 EMPD patients respectively, and in 1, 1 and 1 patient with chronic eczema respectively, and there were significant differences in the prevalence of the above 3 structures between the two diseases (all P < 0.001) .

Vulvar EMPD and chronic eczema both show characteristic dermoscopic features, and dermoscopy is of great value to the diagnosis and differential diagnosis of EMPD.

Paget disease, extramammary; Dermoscopy; Eczema