A parallel ridge pattern under dermoscopy is a prominent dermoscopic finding in macules of malignant melanoma on the palms and soles. Herein, we present a case of pagetoid dyskeratosis with a parallel ridge pattern under dermoscopy.
A 34-year-old Japanese woman was seen with a 1-year history of brownish pigmentation on her left small finger, which had expanded and intensified in color during the previous 2 weeks (Figure 1A). She was an office worker and a nonsmoker. There was no history of contact with chemical substances or dyes.