JAMES M.GRICHNIKMD, PhD
Plaque psoriasis (PP) and lichen ruber planus (LP) are inflammatory skin disorders that can sometimes be clinically difficult to differentiate. In these instances, punch biopsy with subsequent histopathologic evaluation is usually needed. Recently, dermoscopy has been reported to be helpful in the distinction between these 2 entities. The lesions in Figure 1 and Figure 2 were plaques located on the arms of a 53-year-old man and a 23-year-old woman, respectively. Both patients revealed only few additional lesions. Dermoscopically, the lesion in Figure 1 exhibits a network of whitish striae and red globules at the periphery (Figure 3). These dermoscopic findings raised the diagnosis of LP, whereas the multiple, uniformly sized and distributed dotted vessels, together with a central surface scale (Figure 4), led to the diagnosis of PP in the case shown in Figure 2. Histopathologic diagnosis confirmed the dermoscopic diagnosis in both cases. In these 2 examples, dermoscopy allowed distinguishing between LP and PP, especially for the presence of whitish striae (corresponding to the Wickham striae) in the former, and multiple uniformly sized and distributed dotted vessels in the latter.
Zalaudek I, Argenziano G. Dermoscopy Subpatterns of Inflammatory Skin Disorders. Arch Dermatol. 2006;142(6):808. doi:10.1001/archderm.142.6.808