lichen planus - like keratosis ( lplk ) is generally reported to resolve spontaneously , and its dermoscopy features are believed to change with lesion progression and regression . although lplk is reported to show typical pigment networks and blue - gray dots by dermoscopy , there are limited reports describing its chronological changes . we report on the dermoscopic findings of 17 cases of lplk , and summarize the chronological evolution of dermoscopic features for a subset of lesions which was followed up longitudinally . cases included in this retrospective study were histopathology proven lplks ( diagnosis confirmed by authors mf and mt ) or lplks with stereotypical dermoscopic findings diagnosed between 2008 and 2014 at our university hospital . all of the dermoscopic pictures were taken with derma9500 ( derma medical inc . , yokohama , japan ) and k - y jelly ( johnson & johnson , new brunswick , nj , usa ) without polarization . all the dermoscopy images of each case were reviewed side by side for changes ( by authors sw and mt ) . dermoscopy photographs were divided into four groups depending on the number of days ( d ) from the initial visit : 1 ) d = 0 ( initial visit or biopsy day ) ; 2 ) d = 61 to 180 ; 3 ) d = 181 to 270 ; 4 ) d = 271 to 360 . dermoscopic findings of light brown pseudonetwork , pinkish area , gray pseudonetwork , annular granular structures , and blue - gray fine dots , were evaluated at every visit to the hospital . after considering the chronological changes observed in the follow - up cases , we have defined five sequential stages , 1 ) pre - existing solar lentigo , 2 ) early inflammatory stage , 3 ) early regressing stage , 4 ) regressing stage , and 5 ) late regressing stage . two illustrative cases are detailed below , followed by the summary data for the entire case series of 17 lplks . a 67-year - old japanese woman presented with pigmentation on her left cheek that had persisted for several years . dermoscopy examination at the initial visit showed light brown pseudonetwork and overlapping pinkish areas throughout . a partial gray pseudonetwork and annular granular structures were also noted ( figure 1a ) . after three months , the pinkish area remained , with decreased brown color and gray pseudonetwork as the main features ( figure 1b ) . follow - up at nine months revealed only blue - gray fine dots ( figure 1c ) . most of the lesion had resolved entirely at the 21-month follow - up visit , with slight remnants of light brown pseudonetwork focally visible ( figure 1d ) . a 50-year - old japanese man presented with pigmentation on his left cheek that had persisted for 10 years . dermoscopy at the initial visit revealed a pinkish area and gray pseudonetwork ( figure 2a ) . after two months , blue - gray dots were the main feature ( figure 2b ) , which had decreased by the six - month follow - up ( figure 2c ) . the lesion had almost entirely disappeared at the eight - month follow - up ( figure 2d ) . a 67-year - old japanese woman presented with pigmentation on her left cheek that had persisted for several years . dermoscopy examination at the initial visit showed light brown pseudonetwork and overlapping pinkish areas throughout . a partial gray pseudonetwork and annular granular structures were also noted ( figure 1a ) . a partial biopsy confirmed the diagnosis of lplk . after three months , the pinkish area remained , with decreased brown color and gray pseudonetwork as the main features ( figure 1b ) . follow - up at nine months revealed only blue - gray fine dots ( figure 1c ) . most of the lesion had resolved entirely at the 21-month follow - up visit , with slight remnants of light brown pseudonetwork focally visible ( figure 1d ) . a 50-year - old japanese man presented with pigmentation on his left cheek that had persisted for 10 years . dermoscopy at the initial visit revealed a pinkish area and gray pseudonetwork ( figure 2a ) . after two months , blue - gray dots were the main feature ( figure 2b ) , which had decreased by the six - month follow - up ( figure 2c ) . the lesion had almost entirely disappeared at the eight - month follow - up ( figure 2d ) . seventeen patients ( 3 males and 14 females ; age range 4385 years , median 65 ) contributing a total of 17 lplks were included in this study . of these , three lplks were diagnosed based on stereotypical dermoscopic findings , while 14 cases were histopathologically diagnosed as lplk . affected sites included the face ( n=13 ) , back of the hand ( n=2 ) , and thigh ( n=2 ) . clinical diagnoses at the initial visit included lplk ( n=3 ) , actinic keratosis ( n=5 ) , seborrheic keratosis ( n=4 ) , bowen s disease ( n=3 ) , and lentigo maligna ( n=2 ) . the representative dermoscopy findings of the 17 lplk cases included light brown pseudonetwork ( figure 3 ) , pinkish background ( figure 4 ) , annular granular structures ( figure 5 ) , gray pseudonetwork composed of diffuse blue - gray dots ( figure 6 ) , and discrete distribution of fine blue - gray dots ( figure 7 ) . the distribution of dermoscopic findings over the study visits are chronologically summarized in table 1 . nine cases were followed - up from 22 to 659 days ( mean ; 248 ) ; only four patients were followed up for at least 12 months after the initial visit . notably , not all patients visited the hospital during the early stage , but some initially visited in later stages . most cases ( 76% ) showed pinkish background with residual solar lentigo at the initial visit . annular granular structures , gray pseudonetwork , and fine blue - gray dots were the main features of the regressing stage . lplk is thought to be an inflammatory process to eliminate residual solar lentigo or seborrheic keratosis that often disappears spontaneously . dermoscopic and histopathological findings were believed to change over time ; however , there were few reports describing these chronological changes . notably , we did not observe any case of lplk on the chest and presume there might be a racial difference regarding the site of anatomic predilection . dermoscopic findings and corresponding histopathological findings in lplk by stage are summarized in table 2 . capillary dilatation during the inflammatory lichenoid reaction would then correspond to the visible pinkish area . melanin incontinence initially appears as blue - gray dots / globules surrounding hair follicles , which would correspond to annular granular structures , and then distribute diffusely in the papillary dermis , which would correspond to the gray pseudonetwork . melanophages would gradually decrease in number visible by dermoscopic examination as fine blue - gray dots . as shown in table 1 , not all of the cases necessarily show the early stage , but some cases appeared to be in the late dermoscopic stages at the initial visit . if dermoscopic features for each stage of lplk were known to correspond to certain pathological stages , then lplk could be diagnosed without biopsy . however , lplk in the middle or late stages would often lose the characteristic dermoscopic findings of solar lentigo or seborrheic keratosis and might show irregular dots or globules , irregular streaks , or rhomboid structures suggestive of lentigo maligna [ 57 ] . therefore , distinction between lplk and lentigo maligna would be crucial , and careful observation or biopsy is necessary . the limitations of the study are that it is a small - sized , retrospective , observational study and that ethnicity of participants is limited to japanese patients with skin phototype iii .
dermoscopic findings for 17 cases of lichen planus - like keratosis ( lplk ) were chronologically evaluated . 
 three males and 14 females were included in the study and the ages ranged from 43 to 85 years ( median 65 years ) . 
 three cases were diagnosed based on stereotypical dermoscopic findings , while the other 14 cases were histopathologically diagnosed as lplk . 
 dermoscopy photographs were divided into four groups depending on the number of days ( d ) from the initial visit : 1 ) d = 0 ( initial visit or biopsy day ) ; 2 ) d = 61 to 180 ; 3 ) d = 181 to 270 ; 4 ) d = 271 to 360 . 
 dermoscopic findings , described as light brown pseudonetwork , pinkish area , gray pseudonetwork , annular granular structures , and blue - gray fine dots , were evaluated at every visit to the hospital.initial dermoscopy features included light brown pseudonetworks due to residual solar lentigo and overlapping pinkish areas attributed to lichenoid inflammation . 
 annular granular structures and gray pseudonetwork appeared to be the main features of the regressing stage ; these features seemed to progress to  blue - gray fine dots  in the late regressing stage . 
 blue - gray dots or globules reflecting melanophages , the hallmark dermoscopic features of lplk , were believed to resolve in approximately one to two years . based on the clinical and dermoscopic observations , we have specified five stages of evolution of lplk , namely 1 ) pre - existing solar lentigo , 2 ) early inflammatory stage , 3 ) early regressing stage , 4 ) regressing stage , and 5 ) late regressing stage.the limitations of the study are that this is a small - sized , retrospective , observational study and that ethnicity of participants is limited to japanese patients with skin phototype iii .