Clinical, Dermoscopic, and Histopathological Correlation in Non-Infectious Papulosquamous Disorders (Psoriasis, Lichen Planus and Pityriasis Rosea): A Cross-Sectional Study

INTRODUCTION

Papulosquamous disorders comprise a diverse group of chronic dermatological conditions characterised by scaly papules and plaques.^[1] These non-infectious inflammatory dermatoses, including psoriasis, lichen planus, and pityriasis rosea, often present with overlapping clinical and histopathological features despite distinct etiopathogenetic mechanisms.^[1,2] Accurate diagnosis is essential because of their recurrent nature, potential for chronicity, and significant impact on patients' quality of life.^[3]

Although clinical morphology guides the initial diagnosis, overlap among papulosquamous disorders may preclude definitive differentiation.^[2,4] Histopathological examination remains the gold standard but requires an invasive skin biopsy. Dermoscopy has emerged as a valuable non-invasive adjunct that magnifies subsurface structures, improving diagnostic accuracy and permitting treatment monitoring.^[2,4,5]

Epidemiologically, psoriasis affects roughly 2–3 % of the global population^[1], whereas pooled Indian data suggest a lower prevalence of 0.44–2.8 %.^[2] Lichen Planus affects 0.1–4 % of individuals worldwide and is more common in middle-aged adults.^[3] Pityriasis Rosea accounts for 0.5–2 % of dermatology consultations and is typically self-limiting; Indian hospital-based studies report comparable figures.^[4,6]

Pathogenetically, psoriasis is driven by Th1/Th17/Th22 pathways, with key cytokines such as TNF-α, IL-17, and IL-23 inducing keratinocyte hyperproliferation.^[7,8] Lichen Planus represents a T-cell–mediated interface dermatitis targeting basal keratinocytes, and dermoscopic findings show Wickham striae and blue-grey dots that correspond histologically to wedge-shaped hypergranulosis and melanin incontinence respectively.^[9-11] Pityriasis rosea is thought to reflect reactivation of HHV-6/7, beginning with a herald patch followed by a “Christmas-tree” eruption; dermoscopy typically reveals a yellowish background with peripheral collarette scaling.^[12-14]

Histopathology remains indispensable for confirmation, demonstrating parakeratosis, hypogranulosis, and Munro microabscesses in psoriasis; hypergranulosis and interface dermatitis in lichen planus; and spongiosis in pityriasis rosea.^[1]

Integrating dermoscopic and histopathological findings has been shown to enhance diagnostic precision in several Indian studies.^[15,16] Accordingly, the present study aims to comprehensively correlate the clinical, dermoscopic, and histopathological features of psoriasis, lichen planus, and pityriasis rosea in an Indian cohort, thereby contributing toward more standardised diagnostic criteria for non-infectious papulosquamous disorders.

MATERIAL AND METHODS

An analytical cross-sectional study was conducted over a one-year period (September 2023 to September 2024) in the Dermatology Outpatient Department of a tertiary care centre in North India. The study protocol was approved by the Institutional Ethics Committee (IEC/MLNMC/2025/TP-203). A total of 162 patients clinically diagnosed with non-infectious papulosquamous disorders, including psoriasis (chronic plaque psoriasis), lichen planus (classical lichen planus), and pityriasis rosea (classical), were enrolled. Patients aged 10 years and above who provided written informed consent for participation and skin biopsy were included in the study. Exclusion criteria comprised patients who had received topical therapy within the last one month or systemic therapy within the last six months prior to presentation, those unwilling to undergo biopsy, and individuals diagnosed clinically with eczema, seborrheic dermatitis, infectious papulosquamous conditions (e.g., secondary syphilis, tinea corporis, Reiter's disease, scabies), or neoplastic skin lesions.

After obtaining informed consent, each patient underwent a detailed clinical history and dermatological examination. A clinical diagnosis was recorded, and dermoscopic examination was performed using the dual-mode Illuco IDS (Intelligent Dermoscopy System)-1100 dermatoscope. Images were captured through the built-in digital interface and stored in encrypted JPEG format with patient identifiers. Dermoscopic features, including vascular morphology and arrangement, background colour, scale colour and distribution, and the presence of Wickham striae, were documented and photographed. The selection of dermoscopic parameters was guided by existing literature and expert consensus.

A skin punch biopsy was performed under aseptic conditions using local anaesthesia with 2% lignocaine. Specimens were fixed in 10% neutral buffered formalin, routinely processed, embedded in paraffin, sectioned at 4–6 µm, and stained with hematoxylin and eosin. Histopathological examination focused on identifying diagnostic features involving the epidermis, dermoepidermal junction, and dermis.

All clinical, dermoscopic, and histopathological data were recorded in a structured proforma. Patient identifiers were kept confidential. Data were entered into Microsoft Excel and analysed using IBM SPSS Statistics for Windows, Version 22.0 (IBM Corp., Armonk, NY, USA). Descriptive and inferential statistical analyses were performed, and a p-value <0.05 was considered statistically significant.

RESULTS

A total of 162 patients diagnosed with non-infectious papulosquamous disorders were included in the study. The age distribution showed a peak in the 20–29 years group, comprising 35.2% (n = 57) of the study population, followed by 18.5% (n = 30) in the 40–49 years group, and 17.9% (n = 29) in the 30–39 years group [Table 1]. A male predominance was observed, with 93 males (57.4%) and 69 females (42.6%).

Regarding disease duration, 71.6% (n = 116) presented with lesions of less than one year. Only 1.2% (n = 2) had lesions persisting for five years or more, indicating that most patients presented in the early or subacute phase.

Lesions were most commonly observed on the back (74.7%, n = 121), followed by the legs (40.7%, n = 66) and scalp (22.8%, n = 37).

Nail changes were observed in approximately 20% of psoriasis cases, most commonly pitting and onycholysis, followed by subungual hyperkeratosis in a few patients. Oral mucosal involvement was present in about 12% of lichen planus cases, typically showing reticular white striae on the buccal mucosa. Genital lesions were identified in 2% of lichen planus patients, predominantly involving the glans penis.

Clinically, psoriasis was the most frequent diagnosis (36.4%, n = 59), followed by lichen planus (30.2%, n = 49) and pityriasis rosea (12.3%, n = 20). A diagnostic dilemma was recorded in 20.9% (n = 34) of cases. Histopathological confirmation showed psoriasis in 46.3% (n = 75), lichen planus in 37% (n = 60), and pityriasis rosea in 16.7% (n = 27) [Table 1].

Histopathological features varied by diagnosis. Psoriasis was most commonly associated with parakeratosis (93.3%, n = 70), dilated capillaries (86.7%, n = 65), acanthosis (54.7%, n = 41), club-shaped rete ridges (62.6%, n = 47), and hypogranulosis (37.3%, n = 28) [Figure 1]. Lichen planus showed hyperkeratosis (83.3%, n = 50), lymphocytic infiltration at the dermoepidermal junction (66.7%, n = 40), hypergranulosis (55%, n = 33), melanin incontinence (41.7%, n = 25), Civatte bodies (41.7%, n = 25), vacuolar degeneration (38.3%, n = 23), and orthokeratosis (10%, n = 6) [Figure 2]. Pityriasis rosea was characterised by focal parakeratosis (100%, n=27), hypogranulosis (92.6%, n=25), spongiosis (100%, n=27), and extravasation of RBCs (66.6%, n=18) [Table 2] [Figure 3].

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Figure 1: (a) Clinical image of chronic plaque psoriasis (red rectangle), (b) Dermoscopy of chronic plaque psoriasis shows regular arrangement of dotted vessels (red circle) over homogeneous red background (blue arrows) and white scales (black arrows), (c) Histopathological image of chronic plaque psoriasis showing hyperkeratosis (green arrow), hypogranulosis (red arrow), and Munro's microabscesses (black circle). (Haematoxylin and eosin, 40x).

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Figure 2: (a) Clinical image of lichen planus (black circle), (b) Dermoscopy of lichen planus shows violaceous hue and crossing white line on dull red background (Wickham’s striae; black arrow) and presence of peripheral dotted vessels (red arrow) (ILUCO IDS 1100, 30x), (c) Histopathology image of lichen planus showing hyperkeratosis (red arrow), hypergranulosis, and a band like lymphohistiocytic infiltrate (white arrow) (Haematoxylin and eosin, 40x).

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Figure 3: (a) Clinical image of pityriasis rosea (trunk) (red circle), (b) Dermoscopy of pityriasis rosea shows a yellowish background and peripheral white scales (black arrows) (ILLUCO IDS 1100, 30x), (c) Histopathological image of pityriasis rosea showing mid zone of parakeratosis (red arrow) with underlying spongiosis (blue arrow), dermal extravasated red blood cells (white arrow) (Haematoxylin and eosin, 10x).

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Dermoscopic evaluation revealed distinct and statistically significant patterns among the three disorders (p <0.001). A dull red background was strongly associated with lichen planus (91.7%) and was absent in pityriasis rosea, and was observed in only 12% of psoriasis cases. A light red background, typical of psoriasis, was seen in 88% of psoriasis cases, 29.6% of pityriasis rosea, and 8.3% of lichen planus. A yellow background was unique to pityriasis rosea, observed in 70.4% of cases and absent in the others.

Dotted vessels were present in all cases of pityriasis rosea (100%) and in 94.7% of psoriasis cases. In lichen planus, 79.7% of cases showed a combination of dotted and linear vessels, while linear vessels alone were rare (3.4%). Regular vascular arrangement was characteristic of psoriasis (82.7%), whereas patchy distribution predominated in lichen planus (84.7%) and pityriasis rosea (59.3%). A peripheral vascular pattern was seen in 10.2% of lichen planus cases. Clustered vessel arrangements were rare and found only in 2.7% of psoriasis cases.

White scales were most frequently observed in psoriasis (88%), followed by lichen planus (27.1%) and pityriasis rosea (14.8%). Yellow scales were predominant in pityriasis rosea (66.7%) and also noted in lichen planus (45.8%). Mixed white and yellow scales were uncommon across all conditions. Diffuse scaling was characteristic of psoriasis (68%), while peripheral scaling, suggestive of collarette scales, was typical of pityriasis rosea (63%). Central scaling was observed in 22.7% of psoriasis, 18.5% of pityriasis rosea, and 10.2% of lichen planus cases.

Wickham striae, considered pathognomonic for lichen planus, were identified in 74.6% of its cases, but were absent in pityriasis rosea and seen in only 2.7% of psoriasis cases (p <0.001) [Table 3].

A few atypical or uncommon dermoscopic features were observed. In psoriasis, some chronic lesions displayed patchy linear vessels interspersed with dotted vessels, particularly over the lower limbs — a finding not commonly emphasised in earlier Indian series. Faint white crossing lines resembling incomplete Wickham striae were occasionally seen in resolving lichen planus, possibly representing post-inflammatory regressing lesions. In pityriasis rosea, a peripheral reddish halo around collarette scales was noted in about 10% of cases, correlating histologically with dermal vascular congestion and RBC extravasation. These minor variants did not alter diagnostic concordance but expanded the dermoscopic spectrum of these disorders.

Dermoscopic diagnoses aligned well with histopathological findings. Psoriasis was dermoscopically diagnosed in 37.7% (n = 61), lichen planus in 29.6% (n = 48), and pityriasis rosea in 13% (n = 21), while 19.8% (n = 32) were considered non-specific. The concordance between dermoscopic and histopathological diagnoses was statistically significant: psoriasis (80%), lichen planus (76.7%), and pityriasis rosea (77.8%) (Cramer's V = 0.708, p <0.001) [Table 4].

Analysis of dermoscopic and histopathological findings with respect to clinical variables revealed certain consistent trends. Long-standing lesions of psoriasis showed thicker white scales, reduced erythema, and fewer dotted vessels, whereas early lesions demonstrated brighter red backgrounds with prominent vascularity. In lichen planus, older lesions showed fading of Wickham striae and increased melanin incontinence. Site-specific variations were noted: scalp and extensor lesions in psoriasis exhibited denser scaling, while flexural lesions showed less scaling but richer vascular patterns. No significant correlation was observed between age or sex and any dermoscopic or histopathological pattern (p >0.05).

Similarly, strong agreement was observed between clinical and histopathological diagnoses, with confirmation rates of 81.7% for lichen planus, 74.1% for pityriasis rosea, and 72% for psoriasis (Cramer's V = 0.607, p <0.001). These findings highlight the diagnostic strength of integrated clinical, dermoscopic, and histopathological assessment in the evaluation of non-infectious papulosquamous disorders [Table 5].

DISCUSSION

This analytical cross-sectional study evaluated the clinical, dermoscopic, and histopathological features of non-infectious papulosquamous disorders—principally psoriasis, lichen planus (LP), and pityriasis rosea (PR)—in 162 patients attending a tertiary-care centre. The results confirm the diagnostic value of integrating dermoscopy with routine clinical and histological assessment.

A predominance of young adults (20–29 y) was observed, mirroring the Indian series by Awake^[15] and Kaur et al.^[16]Male predominance accords with Barman et al., possibly reflecting occupational exposure and differential health-seeking behaviour.^[17] More than 70 % of patients presented within one year of onset, underscoring the importance of early recognition in shaping dermoscopic patterns. The back, legs, and scalp were the most frequent sites; lesions on trauma-prone areas such as the back and elbows likely relate to Koebnerisation in psoriasis.^[2]

Clinically, psoriasis was the commonest diagnosis, followed by lichen planus and pityriasis rosea. Histopathology reproduced classical findings: parakeratosis, acanthosis, and dilated capillaries in psoriasis; wedge-shaped hypergranulosis, Civatte bodies, and band-like lymphocytic infiltrates in lichen planus^[6]; and patchy spongiosis with parakeratosis in pityriasis rosea.^[1]

Dermoscopy provided disease-specific patterns. Psoriasis showed a light-red background with regularly distributed dotted vessels and diffuse white scales, concordant with Lallas et al.^[2] and the Indian palmar series by Errichetti & Stinco.^[5] Lichen planus displayed a dull-red background, Wickham striae, and a dotted ± linear vascular mix, corroborating Litaiem et al.^[9] and Sgouros et al.^[11] Pityriasis Rosea exhibited a yellowish background with peripheral collarette scaling and dotted vessels, echoing Mugwanya's African and Indian cohorts.^[13,14]

Vascular arrangement differed significantly: regular patterns typified psoriasis, whereas patchy or peripheral distribution dominated lichen planus and pityriasis rosea—paralleling the inflammatory pattern taxonomy. Scale colour and distribution likewise distinguished entities: diffuse white in psoriasis, peripheral yellow in pityriasis rosea, and mixed patterns in lichen planus—findings supported by Errichetti's dermoscopic reviews.^[4,10] Wickham striae were present in 74.6 % of lichen planus lesions, confirming their high specificity.^[9] Their absence in pityriasis rosea and rarity in psoriasis (2.7 %) reinforces diagnostic separation.

Based on the observed clinicodermoscopic–histopathological correlations, certain recommendations can be made regarding the role of biopsy and dermoscopy. Dermoscopy should be employed routinely even in classical presentations, as it helps confirm the diagnosis non-invasively and guides biopsy site selection when needed. Biopsy is particularly useful in lesions with atypical evolution, unusually distributed morphology, or poor response to therapy. In stable, well-developed plaques of psoriasis or typical violaceous papules of lichen planus showing characteristic dermoscopic features, histopathological confirmation may be deferred. For early or evolving lesions, dermoscopy can assist in distinguishing between these entities before histological changes become fully established. This approach optimises diagnostic precision while minimising unnecessary invasive procedures.

The practical implication of this study lies in reinforcing the role of dermoscopy as a rapid, non-invasive, and cost-effective diagnostic adjunct in routine dermatology practice. In typical cases of chronic plaque psoriasis, classical lichen planus, and pityriasis rosea, dermoscopy can enhance diagnostic confidence and reduce the need for biopsy. It allows for early differentiation of morphologically similar lesions, especially in resource-limited settings where histopathology may not be immediately feasible. Incorporating dermoscopy into routine examination can improve patient comfort, enable disease monitoring, and guide site selection for biopsy when required, thereby streamlining diagnostic workflow and improving overall patient care.

CONCLUSION

The findings of this study highlight the value of an integrated diagnostic approach. Dermoscopy enhances early detection and improves diagnostic confidence when used alongside clinical and histopathological evaluation. The strong correlation across all modalities underscores the importance of a multidisciplinary strategy in diagnosing non-infectious papulosquamous disorders effectively.