In Ps, dotted regular blood vessels in dermoscopy (detected in 100% of dermoscopically examined Ps lesions) correlated with dilated tortuous capillaries within the elongated dermal papillae in histopathology (detected in 100% of histopathologic Ps sections) (P=1.0). Diffuse thick white scales in dermoscopy (100%) correlated with hyperparakeratosis in histopathology (100%) (P=1.0), and light or dull red background in dermoscopy (100%) correlated with edematous dermal papillae with dilated capillaries in histopathology (100%) (P=1.0).
In LP, Wickham’s striae seen in dermoscopy (100%) correlated with compact orthokeratosis, hypergranulosis and acanthosis in histopathological sections (100%) (P=1.0). White scales in dermoscopy (83.3%) correlated with epidermal hyperkeratosis in histopathology (100%) (P=0.07). Dotted blood vessels in dermoscopy (83.3%) correlated with papillary dermal capillaries (100%) (P=0.07), whereas diffuse brown pigment in dermoscopy (77.8%) correlated with epidermal melanin incontinence and dermal melanophages in histopathology (88.9%) (P=0.371).
In SD, yellow scales found in dermoscopy (100%) correlated with hyperkeratosis, psoriasiform epidermal hyperplasia, and neutrophilic exocytosis in histopathology (100%) (P=1.0). Dotted blood vessels in dermoscopy (90%) correlated with dilated capillaries in the elongated dermal papillae (100%) (P=0.3). Light red background in dermoscopy (70%) correlated with vascular response, spongiosis, and dermal edema that were found in all examined histopathological sections (100%) (P=0.06).
In PR, white scales detected in dermoscopy (100%) correlated with epidermal hyperkeratosis (100%) and mounds of parakeratosis (83.3%) in examined histopathological sections (P=1.0 and 0.139, respectively). Dotted blood vessels in dermoscopy (100%) correlated with capillaries in the papillary dermis (100%) (P=0.615), whereas fading red (yellow) background in dermoscopy (75%) correlated with papillary dermal edema with perivascular infiltrate (83.3%) and focal spongiosis in 100% of examined histopathological PR sections (P=0.615 and 0.064, respectively).
Figure 1 gives some examples of the clinical presentation, histopathologic features, and correlating dermoscopic images of the PSDs included in the study.
Dermoscopy is continually gaining appreciation in the field of general dermatology as it facilitates the clinical recognition of several inflammatory and infectious diseases, as well as their discrimination from skin tumors 5,8. Papulosquamous skin diseases (PSDs) assume considerable importance because of their high frequency of occurrence and they constitute ∼40% of the total skin biopsies 11. Whether dermoscopy could help in minimizing this need for biopsy taking in PSDs is still a matter of debate.
Many studies were carried out to describe the dermoscopic features of Ps 12–19. Although dotted vessels are a well-recognized criterion for the diagnosis of Ps as they are seen mostly in all cases 12, most studies showed that dotted vessels are not limited to Ps but occur at variable frequency in several other inflammatory and neoplastic lesions 8,12,19–21. Accordingly, dotted vessels as the only dermoscopic criterion are insufficient to distinguish between these different entities accurately. Most studies concluded that red dots, homogeneous vascular pattern, and light red background were significant dermoscopic features for psoriasis, yielding a diagnostic probability of 99% if all the three features were present 8,12,19.
Possible correlations between some dermoscopic findings and histopathological features of psoriasiform skin reaction were previously described 21. Overall, psoriasiform pattern was characterized by intense red background with more or less regularly distributed red dots and globules (positive Auspitz sign) which were suggested to correlate with the view from the top of the tortuous elongated capillaries within regularly distributed, club-shaped elongated dermal papillae 21, whereas diffuse thick white scales were suggested to correlate to hyperkeratosis and parakeratosis 21.
In the present study, dotted regular blood vessels were found in all dermoscopically examined Ps lesions (100%), and related to dilated tortuous capillaries within the elongated dermal papillae that were found also in all histopathologically examined Ps sections (P=1.0). Similarly, diffuse thick white scales were found in all dermoscopically examined Ps lesions (100%) and related to hyperparakeratosis that was found also in all examined histopathological Ps sections. Red background (either light or dull) was detected in 100% of dermoscopically examined Ps lesions and related to capillary dilatation that was noticeable in 100% of examined histopathological Ps sections±associated dermal edema. It should be noted that pathological correlation did not provide explanation for that variation in the color of psoriatic lesions background noticed through dermoscopy (light red vs. dull red).
The dermoscopic features of LP have been previously described in several reports 22–25. Lallas et al. 12 studied the accuracy of dermoscopic criteria for diagnosis of LP and differentiating it from other PSD and stated that white crossing lines (Wickham’s striae) were seen exclusively in LP in 96% of the examined lesions and occurred together with a dull red background color in 64% and peripheral arrangement of vessels in 60% of lesions.
Güngör et al. 24 studied the dermoscopic patterns of classic LP and other disease variants and stated that Wickham’s striae were observed in 89.4% of examined lesions.
Dermoscopic criteria of LP detected in the current study came in agreement, where Wickham’s striae were detected in all examined LP lesions, in addition to diffuse brown pigment in 77.8%, red globules in 16.7%, yellow dots in 22.2%, and white dots in 16.7% of examined lesions.
In a previous study, Wickham’s striae in LP were described to correspond mostly to compact orthokeratosis above zones of wedge-shaped hypergranulosis and acanthosis. White scales were related mostly to epidermal hyperkeratosis, dull red background were related to partially obscured numerous papillary blood vessels by inflammatory infiltrate, dotted blood vessels were related to capillaries in the papillary dermis, whereas diffuse brown pigment corresponded mostly to pigmentary incontinence present in histopathology 21.
Dermoscopic examination of LP lesions in the present study detected Wickham’s striae in 100% of lesions and they related well to compact orthokeratosis, hypergranulosis, and acanthosis that were found in all histopathological LP sections; white scales in 83.3% of lesions and related to epidermal hyperkeratosis that was found in all histopathological LP sections; dotted blood vessels were found in 83.3% of examined dermoscopic LP lesions and related to capillaries in the papillary dermis that were found in all examined histopathological sections; and diffuse brown pigment was found in 77.8% of examined dermoscopic LP lesions and related to epidermal melanin incontinence and dermal melanophages that were found in 88.9% of examined histopathological LP sections (Table 2).
Regarding SD, the present study detected dotted vessels in 100% of dermoscopically examined lesions, which assumed patchy distribution in 60% of lesions. Moreover, yellow scales were present in all examined lesions. In a similar context, Lallas et al. 12 stated that vessels in SD appeared more commonly in a patchy distribution in 59% of lesions and associated with yellow scales in 61% of lesions. Moreover, Lacarrubba et al. 19 mentioned that when dotted vessels appear in a patchy distribution together with yellow scales, they are indicative of dermatitis. Lallas et al. 12 studied the dermoscopic patterns of common facial inflammatory skin diseases, and mentioned that among 22 SD lesions, dotted vessels in patchy distribution were present in 86.4%, linear branching vessels in 4.5%, yellow scales in 77.3%, and white scales in 27.3%, and they suggested that dotted vessels in patchy distribution and yellow scales could be considered characteristic features of SD.
Lallas et al. 12 mentioned that histopathological criteria for dermatitis included presence of acanthosis, spongiosis and exocytosis, plus a mixed inflammatory cell infiltrate surrounding the superficial vascular plexus, composed of lymphocytes, histiocytes, and eosinophils.
In a previous analysis, yellow scales in SD were correlated to hyperkeratosis, parakeratosis, psoriasiform epidermal hyperplasia, and neutrophilic exocytosis; dotted blood vessels were correlated to the view from the top of the tortuous elongated capillaries within the elongated dermal papillae; light red background related to the vascular response denoting the effect of spongiosis and dermal edema; and linear blood vessels were thought to correspond to normal or slightly dilated subpapillary vessels 21.
In the present study, comparing between dermoscopic and histopathological features of the studied SD lesions revealed that yellow scales were found in all dermoscopically examined SD lesions (100%) and were combined with white scales in only 20% of lesions These yellow scales related to hyperkeratosis, psoriasiform epidermal hyperplasia, and neutrophilic exocytosis that were found in all histopathological SD sections. Additionally, dotted blood vessels were found in 90% of SD lesions and related to capillaries in the papillary dermis in all histopathological sections, and light red background was detected in 70% of SD lesions and related well to spongiosis and dermal edema that were manifest in all histopathological sections.
Regarding PR, the most common features detected in the current study through dermoscope were white peripheral scales (positive collarette sign) which were present in 100% of lesions, yellow background in 75%, and dotted vessels in 100% of lesions, which assumed patchy distribution in 75% of examined lesions. It should be noted that dotted vessels of PR were globally much less remarkable and considerably fewer in number compared with Ps or SD. Our observations agree well with those of Lallas et al. 12 who studied the accuracy of dermoscopic criteria for diagnosis of PR and stated that dotted vessels were mostly associated with a yellowish background color in 65% of patients with PR (13/20), whereas peripheral arrangement of scales was detected in 70% of patients with PR (14/20). They assumed that PR was characterized by peripheral scaling around a diffuse and structureless yellowish center.
Possible correlations were previously described between some dermoscopic findings and histopathological features in PR where white scales were related mostly to epidermal hyperkeratosis, dotted blood vessels related mostly to capillaries in the papillary dermis, whereas fading or light red background was thought to reflect the vascular response and denote the effect of spongiosis and dermal edema 21.
In the present study, associations between dermoscopic findings and histopathological features of the studied patients with PR were manifest, as white scales were present in 100% of dermoscopically examined PR lesions and related well to epidermal hyperkeratosis present in all histopathologic sections, dotted blood vessels (100%) related to capillaries in the papillary dermis, and fading red (yellow) background (75% of PR lesions) related to vascular response with spongiosis and dermal edema effects (found in 83.3% of histopathologic PR sections).
From the results of the present study, it could be concluded that Ps, LP, SD, and PR reveal specific dermoscopic patterns that may aid their clinical and differential diagnosis. Ps was characterized by the combination of diffuse white scales and regularly distributed dotted vessels over a light or dull red background. LP was characterized by the combination of white crossing lines (Wickham striae), which were unique for LP and peripheral dotted vessels over a dull red background. SD was characterized by the presence of pathognomonic yellow scales in addition to dotted vessels in a patchy distribution over a light red background, and PR was characterized by the presence of peripherally arranged white scales (collarette scales) with a patchy distribution of dotted vessels over a characteristic fading red/yellowish background color. Moreover, dermoscopic features of these PSD related well to their relevant histopathological findings. So dermoscopy should be regarded as a safe rapid diagnostic tool that assists in the clinical diagnosis of Ps, LP, SD, and PR and differentiation between these highly confusing entities to minimizes the need for lesional biopsies for histopmorphological diagnosis.
Still further larger scale studies on larger numbers of patients with different common, rare and atypical types of PSD are required to evaluate the real value of dermoscopy in fine diagnosis and differentiation of these diseases.
Conflicts of interest
There are no conflicts of interest.
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Keywords:© 2018 Egyptian Women's Dermatologic Society
dermoscopy; histopathology; papulosquamous diseases