Dermoscopy and UVFD in Differentiating Palmoplantar Psoriasis and Palmoplantar Eczema

This prospective, single-center, observational comparative study was designed to evaluate polarized dermoscopic and ultraviolet-induced fluorescence dermoscopic (UVFD) findings in the differential diagnosis of palmoplantar psoriasis and palmoplantar eczema.

Adult patients aged 18 years and older with clinically and/or histopathologically confirmed palmoplantar plaque psoriasis or palmoplantar eczema were enrolled. Patients with recent topical or systemic treatment, positive fungal examination, palmoplantar pustulosis, other confounding palmoplantar dermatoses, malignancy or immunosuppressive conditions, pregnancy, lactation, non-specific histopathological findings, or histopathological findings inconsistent with the clinical diagnosis were excluded.

Demographic and clinical characteristics, lesion localization, symptom profile, relevant dermatological history, nail involvement, and disease severity parameters were recorded. Standardized polarized dermoscopic and UVFD images were obtained using a handheld dermoscope (DermLite DL5, 3Gen Inc., San Juan Capistrano, CA, USA). Imaging was performed under standardized conditions, and predefined dermoscopic and UVFD parameters relevant to inflammatory palmoplantar dermatoses were systematically evaluated.

In polarized dermoscopy, vascular morphology and distribution, scale color and distribution, background color, yellow-brown globules, yellow-orange structureless areas, yellow-orange crusts, and hemorrhage within scales were assessed. In UVFD, scale distribution, scale pattern, dominant fluorescence color, additional fluorescence color, and white-yellow fluorescent foci were evaluated. Image assessments were performed by independent dermatologists blinded to the clinical diagnosis.

The main objective of the study is to compare polarized dermoscopic and UVFD findings between palmoplantar psoriasis and palmoplantar eczema and to identify features that may support the clinical differentiation of these overlapping palmoplantar dermatoses. The study does not assign any treatment or intervention; all imaging procedures are non-invasive and performed for observational diagnostic evaluation.

Inclusion criteria

• Age 18 years or older.
• Clinical diagnosis of palmoplantar psoriasis or palmoplantar eczema involving the palms and/or soles.
• For the palmoplantar psoriasis group: presence of sharply demarcated erythematous and scaly plaques on the palms and/or soles, with diagnosis confirmed clinically and/or histopathologically.
• In clinically uncertain palmoplantar psoriasis cases, at least one supporting feature such as psoriatic lesions outside the palmoplantar area, psoriatic nail involvement, psoriatic arthritis, personal history of psoriasis, or family history of psoriasis.
• For the palmoplantar eczema group: presence of chronic or recurrent palmoplantar eczema with hyperkeratotic and/or fissured palmoplantar plaques, with diagnosis confirmed clinically and/or histopathologically.
• Ability and willingness to provide written informed consent.

Exclusion criteria

• Age younger than 18 years.
• Presence of another palmoplantar dermatosis that may interfere with the diagnosis of palmoplantar psoriasis or palmoplantar eczema.
• Histopathological findings inconsistent with the clinical diagnosis, when histopathological examination was performed.