Trichoscopy may enhance the differential diagnosis of erythroderma.

There is a paucity of data concerning the usefulness of trichoscopy in patients with erythroderma. The aim of the study was to compare the trichoscopic features in erythroderma of various aetiologies. In total, 49 patients with a determined cause of erythroderma [including atopic dermatitis (AD), mycosis fungoides (MF), allergic contact eczema (ACE), psoriasis (Pso), Sézary syndrome (SS), drug reaction, pityriasis rubra pilaris (PRP), dermatomyositis (DM), actinic reticuloid (AR), crusted scabies (CS) and pemphigus foliaceus (PF)] were included in the study. Dotted vessels were present in patients with AD, PRP, MF, SS and Pso, and absent in DM, CS and PF (χ², P < 0.02). Spermatozoon-like vessels were observed only in MF and SS (P = 0.001). Whitish-pinkish structureless areas were described in all patients with DM, AR and CS (P < 0.03). The type of vessel and the presence of whitish-pinkish structureless areas under trichoscopy may indicate the cause of erythroderma.