Abstract: 【Abstract】 Objective To investigate clinical manifestations and dermoscopic characteristics of lichen planus-like keratosis （LPLK）. Methods Clinical data were collected from 21 patients with LPLK who visited Shanghai Skin Disease Hospital and underwent both dermoscopic and histopathological examinations from January 2017 to September 2019, and clinical and dermoscopic features were retrospectively analyzed. Results These patients were aged 64.69 ± 13.29 years, and the ratio of males to females was 1∶2. Skin lesions were located on the face of 18 cases and legs of 3 cases, and were red/violaceous in color in 7 cases, reddish-brown in 5, brown/gray in 8, and brown/reddish in 1. There were 3 types of kin lesions, including plaque-like type in 10 cases, flat pigmented patch type in 6, and flat erythema-like type in 5. As dermoscopy showed, 12 cases were non-pigmented LPLK, and 9 were pigmented LPLK. Pigment granules were found in 13 lesions, and there was no significant difference in the incidence of pigment granules between pigmented and non-pigmented LPLK （P = 0.07）; pigment granules were often diffusely distributed （9/13）, and the diffuse distribution pattern was common paticularly in pigmented LPLK（8/9）; locally distributed pigment granules were found in 4 cases of non-pigmented LPLK. Coarse pigment granules were seen in 10 cases （10/13）, including 8 of pigmented LPLK and 2 of non-pigmented LPLK, and the incidence rate of coarse pigment granules significantly differed between the pigmented LPLK and non-pigmented LPLK groups （P = 0.002）. Moreover, special distribution patterns of pigment granules included the annular granular pattern （8/13） and peppered pattern （7/13）, and no significant difference was observed in the incidence of the 2 special distribution patterns between the pigmented LPLK and non-pigmented LPLK groups （both P > 0.05）. Scales were seen in 13 cases （13/21）, and vascular structures in 7 （7/21）, and there was no significant difference in the incidence of the 2 structures between the pigmented and non-pigmented LPLK groups （P = 0.67, 0.16, respectively）. Conclusion LPLK mostly occurs on the face, and manifests as solitary red, reddish-brown or brownish-gray plaques or patches, whose surfaces may be covered with scales. The characteristic dermoscopic feature of LPLK is the presence of pigment granules, which are coarse, often diffusely distributed, and commonly observed in pigmented LPLK.

Key words: Keratosis, Dermoscopy, Skin manifestations, Lichen planus-like keratosis