Dermoscopy as a diagnostic tool to differentiate between tinea pedis and plantar psoriasis

Abstract

<p><strong>Background</strong>: Clinical differentiation between tinea pedis and plantar psoriasis may sometimes be challenging, with consequent diagnostic delays and unnecessary therapies; in such cases histopathological analysis helps to differentiate the 2 conditions. In this study we used a dermoscope as a non-invasive tool to investigate the significance of specific dermoscopic features and to improve their non-invasive differentiation.</p><p><strong>Methods:</strong> A clinical diagnosis of plantar psoriasis/tinea pedis was made on basis of accepted literature and proved by histopathology. Image capturing was performed using a dermoscope. Based on combination of history, clinical, and dermoscopic examination conclusive diagnosis with specific dermoscopic features for each disease was achieved.</p><p><strong>Results:</strong> The 15 patients of biopsy proven tinea pedis and 17 patients of biopsy proven plantar psoriasis were selected. We found that the presence of whitish powdery scales located in the furrows with apparently uninvolved skin in between was significant in tinea pedis whereas the presence of silvery white scales on a pinkish red erythematous background with regularly distributed red dots was significant in plantar psoriasis.</p><p><strong>Conclusions:</strong> Dermoscopy showed significant patterns in tinea pedis and plantar psoriasis due to their well-known different histological and physio pathological background, with white diffuse scales reflecting the dry and hyperkeratotic nature of plantar psoriasis and the red dots signifying the pin point blood vessels seen clinically as Auspitz sign. The peculiar scaling in tinea pedis might result from the predilection of dermatophytes to proliferate in moist environment, such as the furrows.</p>