JAMES MGRICHNIKMD, PhDASHFAQ AMARGHOOBMDALONSCOPEMD
A 33-year-old woman and a 35-year-old man presented with a 3- and 4-week history of multiple (>20) diffuse erythematous papules. Some lesions were covered by necrotic crusts. Dermoscopic examination revealed papules with a central whitish patch (Figure 1 [original magnification ×20]) and crusted lesions with an amorphous brownish structure (Figure 2 [original magnification ×20]). Both types of lesion were surrounded by a well-defined ring of pinpoint and/or linear vascular structures with a targetoid appearance. At higher magnification, the ring of vascular structures appeared dilated and convoluted, with some of them showing a glomerular pattern or linear arrangement (Figure 3 [original magnification ×200 (top) and ×300 (bottom)]), and nonblanchable reddish globules were observed in all fields (Figure 4, arrows [original magnification ×200]). Histopathologic analysis confirmed the clinical diagnosis of pityriasis lichenoides et varioliformis acuta in both patients. The vascular pattern seen by dermoscopy correlates with the presence of dilation and engorgement of blood vessels and microhemorrhages in the papillary dermis (Figure 5). In our experience, the dermoscopic appearance is indicative of pityriasis lichenoides et varioliformis acuta, which helps in the differential diagnosis of other clinically similar diseases (eg, guttate psoriasis, lichen planus, pityriasis rosea, and chickenpox).
Lacarrubba F, Micali G. Dermoscopy of Pityriasis Lichenoides et Varioliformis Acuta. Arch Dermatol. 2010;146(11):1322. doi:10.1001/archdermatol.2010.263