Background

The diagnosis of purpuric mycosis fungoides (PMF) is often challenging to be clinically differentiated from inflammatory diseases such as pigmented purpuric dermatosis (PPD). Dermoscopy as a non-invasive method can be employed for the visualisation of features invisible to the naked eye.

Objectives

This study aimed to survey the dermoscopic findings of PMF in comparison with PPD.

Methods

Forty-one patients with an established diagnosis of PMF (n = 28) and PPD (n = 13) were prospectively recruited. Dermoscopic images were taken by FotoFinder Medicam 1000 (FotoFinder Systems GmbH, Bad Birnbach, Germany).

Results

Characteristic dermoscopic patterns consisting of fine short linear vessels (35.7%, P = 0.017) and spermatozoa-like structures (50%, P = 0.014) were found to be significantly more common in PMF lesions, while PPD lesions were typified by erythematous globules (76.9%, P = 0.01), in the background colour of dull red (61.5%, P = 0.01) and reticular pigmentation (61.5%, P = 0.044).

Conclusions

This study showed the usefulness of dermoscopy for the diagnosis of PMF and PPD cases. Studies with long-term follow-up are needed to affirm the value of these dermoscopic patterns in the differentiation between the two entities.