Pigmented purpuric dermatoses versus purpuric mycosis fungoides: Clinicopathologic similarities and new insights into dermoscopic features.

Abstract

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