The role of dermoscopy in the differential diagnosis of palmoplantar eczema and palmoplantar psoriasis

Introduction: Isolated palmar and/or plantar psoriasis cases are frequently confused with palmoplantar eczema and the exact differential diagnosis usually can be made histopathologically. Dermoscopy is a fast, non-invasive and inexpensive diagnostic method. It is frequently used in the diagnosis of melanocytic lesions, but also in the diagnosis of both inflammatory and non-inflammatory dermatoses. Aim: The purpose of our study was; to distinguish palmoplantar psoriasis patients and palmoplantar hyperkeratotic eczema patients by using dermoscopy so as to make faster differential diagnosis. Methods: The study included 90 patients (35 psoriasis and 55 eczema) between 18 and 75 years of age who did not receive any topical or systemic treatment with palmar and/or plantar lesions that applied to our dermatology out-patient clinic between October 2016 and June 2018. The Statistical Package for Social Sciences (SPSS for Windows, Version 21.0) was used for statistical analyses. The results were interpreted within a confidence interval (CI) of 95% and p was set at 0.05. Results: In our study, dot vessels were most frequently observed in psoriasis patients. Rings vessels were seen in 5 patients with psoriasis, not in any of eczema patients (p=0,007). Patchy distribution vascular pattern was significantly higher in eczema group. The most common background color in psoriasis patients was light red (48.6%) (p <0.001). White scales were found significantly higher in psoriasis patients, also yellow scales in eczema group. The newly defined "ringworm pattern globules" were detected in 10.9% of the patients with eczema but not in any of psoriasis patients (p>0,05). Conclusion: There is only one study in literature about dermoscopy on palmoplantar psoriasis and eczema. In our study, yellow crusts, patchy distribution scale and patchy vascular pattern, yellow scale color, dull red background were significant in patients with palmoplantar eczema, whereas patients with psoriasis had light red background, regular vascular distribution pattern and white scale color. "Ringworm globule" which was not mentioned among the dermoscopic findings of patients with hyperkeratotic palmoplantar eczema previously in the literature may be a new useful dermoscopic finding.