To investigate dermoscopic features of onychomycosis and nail psoriasis.

From March 2017 to March 2018, 128 patients with onychomycosis and 128 with nail psoriasis were enrolled from Department of Dermatology, Xiangyang Central Hospital. Dermoscopic images of the lesional nails were compared. Enumeration data were analyzed by chi-square test and Fisher′s exact test.

There were 7 kinds of dermoscopic patterns in onychomycosis, including jagged edge (69/128, 53.91%) , longitudinal striae (72/128, 56.25%) , cone-shaped keratosis (30/128, 23.44%) , nail plate thickening (21/128, 16.41%) , black dots (5/128, 3.91%) , onycholysis (26/128, 20.31%) , and nail discoloration (23/128, 17.97%) . The jagged edge and longitudinal striae occurred more frequently in distal/lateral subungual onychomycosis (DLSO) than in the other 3 clinical subtypes of onychomycosis (all P < 0.001) , and cone-shaped keratosis occurred more frequently in total dystrophic onychomycosis (TDO) than in the other 3 clinical subtypes of onychomycosis (χ² = 42.020, P < 0.001) . There were no significant differences in the prevalance of nail plate thickening, black dots, onycholysis and nail discoloration among the 4 clinical subtypes of onychomycosis (all P > 0.05) . There were 7 kinds of dermoscopic patterns in nail psoriasis, including pitting corrosion (61/128, 47.66%) , oil drop sign (41/128, 32.03%) , splinter hemorrhage (41/128, 32.03%) , dilated hyponychial capillaries (23/128, 17.97%) , nail plate thickening (20/128, 15.63%) , onycholysis (20/128, 15.63%) , and nail discoloration (13/128, 10.16%) . The oil drop sign occurred more frequently in psoriasis vulgaris and psoriasis arthropathica than in the other 2 clinical subtypes of psoriasis (P = 0.019) . The dilated hyponychial capillaries occurred more frequently in pustular psoriasis than in the other 3 clinical subtypes of psoriasis (P = 0.047) . There were no significant differences in the prevalance of pitting corrosion, splinter haemorrhage, nail plate thickening and nail discoloration among the 4 clinical subtypes of psoriasis (all P > 0.05) .

The dermoscopic features of onychomycosis include jagged edge, longitudinal striae, cone-shaped keratosis and black dots, and the dermoscopic features of nail psoriasis include pitting corrosion, oil drop sign, splinter haemorrhage and dilated hyponychial capillaries. Their common dermoscopic features include nail plate thickening, onycholysis and nail discoloration.

Onychomycosis; Psoriasis; Nails; Dermoscopy