Abstract
Introduction:
Psoriasis and psoriatic arthritis (PsA) are systemic inflammatory diseases that affect both large vessels and the microcirculation. Nailfold capillaroscopy (NFC) offers a non-invasive tool to detect these vascular changes. This study aimed to identify nailfold capillaroscopic changes in patients with psoriasis and PsA.
Methods:
We conducted a case-control study including 40 patients with psoriasis (20 only with skin psoriasis, 20 with PsA associated with skin psoriasis) and 20 healthy controls. Demographic, clinical, and laboratory data were collected. Capillary density and morphology were assessed using NFC.
Results:
Capillary loop density was significantly lower in PsA patients compared to those with only psoriasis (P ≤ .05). Both psoriasis and PsA groups showed a highly significant increase in rarefaction, avascularity, arterial limb diameter, and apical diameter compared to controls (P ≤ .01). Capillary tortuosity was observed in 60% of psoriasis patients and 65% of those with PsA.
Conclusion:
NFC revealed characteristic microvascular abnormalities in psoriatic disease, supporting its value as a non-invasive tool for assessing systemic vascular involvement. Specific correlations with Psoriasis Area Severity Index score (PASI) and Disease Activity in Psoriatic Arthritis score (DAPSA) highlight its potential role in monitoring disease activity. Larger longitudinal studies are warranted to confirm these findings.
Abbreviations
Disease activity in psoriatic arthritis score
Disease-modifying antirheumatic drugs
Glycated haemoglobin
Highly significant
Interquartile range
Low significant difference
Nailfold capillaroscopy
Non-significant
Psoriasis Area Severity Index score
Psoriatic arthritis
Psoriasis
Vascular endothelial growth factor
Introduction
Psoriasis is a chronic inflammatory disease primarily affecting the skin, characterised by thick, scaly, erythematous plaques. 1 It significantly impairs patients’ quality of life. It is now recognised as a systemic condition due to its association with joint involvement. Proinflammatory cytokines such as TNF-alpha, IL-17, and IL-23 play a pivotal role in psoriasis pathogenesis and are key drivers of psoriatic arthritis (PsA) development. 2
PsA is a chronic inflammatory arthropathy affecting approximately 30% of patients with psoriasis. It presents with a diverse spectrum of clinical manifestations, including peripheral arthritis, axial involvement, enthesitis, dactylitis, and nail disease. 3 Early diagnosis and treatment are crucial to prevent irreversible joint damage, functional disability, reduced quality of life, and increased healthcare costs. 4
Microvascular changes in psoriasis result from the action of angiogenic factors such as vascular endothelial growth factor (VEGF) released by basal keratinocytes, transforming growth factor-beta, and platelet-derived growth factor. These mediators contribute to capillary dilation, haemorrhage, tortuosity, and bushy capillaries. 5
Nailfold capillaroscopy (NFC) is a non-invasive technique that allows direct visualisation of the microcirculation. 6 Initially used in the diagnosis of connective tissue diseases, its application has expanded to other systemic inflammatory conditions, including psoriasis and PsA. 7 However, existing data on NFC changes in PsA are inconsistent, and it remains unclear whether distinct patterns exist. Addressing this gap is important for understanding microvascular involvement across the psoriatic disease spectrum.
This study aimed to assess nailfold capillaroscopic changes in patients with psoriasis and PsA and to explore their potential role in disease assessment.
Patients and Methods
Forty psoriatic patients (20 with skin psoriasis, 20 with PsA and skin psoriasis) and 20 healthy control group were included in this case-control study, which was conducted at the outpatient clinics of Rheumatology, Rehabilitation, and Physical Medicine Department, as well as the Dermatology Department of Ain Shams University.
Age and sex between the studied groups were comparable without a significant difference to minimise demographic bias.
Written informed consent was obtained from all participants prior to inclusion in the study; they were fully informed about the purpose, procedures, and benefits of the study. The Research Ethics Committee at the Faculty of Medicine, Ain Shams University approved the study (No. FWA000017585).
Inclusion criteria:
Diagnosis of psoriasis based on clinical examination: well-demarcated, erythematous plaques with silver-white scales. Diagnosis of PsA according to the CASPAR criteria (2006).
Exclusion criteria:
Primary or secondary Raynaud’s phenomenon. Other rheumatological or vascular diseases (e.g., Buerger’s disease). Diabetes mellitus, hypertension, or smoking. Fingers with a history of trauma were excluded from capillaroscopic analysis.
Clinical and Laboratory Assessment
A detailed medical history was taken, including disease duration and nail changes. Clinical examination included the Psoriasis Area and Severity Index (PASI) and Disease Activity in Psoriatic Arthritis (DAPSA) scores. C-reactive protein (CRP) was tested for PsA patients, and glycated haemoglobin (HbA1C) was performed for all subjects to exclude diabetes.
NFC Technique
Capillaroscopic evaluation was performed using a Dino-Lite AM4115-N2UT microscope. After a 20-minute acclimatisation period in a room maintained at 22°C, images of the second to fifth fingers of both hands were obtained using 200× magnification. Patients were instructed to avoid caffeine for four to six hours before the exam. The probe was applied gently at a 90° or 45° angle without exerting pressure. Four images were taken per nail fold quadrant (lateral, central-lateral, central-medial, medial). The following parameters were assessed: capillary density was calculated as the mean number of capillaries per millimetre across all quadrants of the eight examined fingers (2nd to 5th of both hands), morphology (tortuosity, branching, bushy capillaries), dimensions (apical diameter, capillary width) were obtained manually using digital calipers within the Dino-Lite software with calibration performed before each session, and presence of avascular areas or haemorrhages. All examinations were performed by the same investigator to reduce inter-observer variability.
Severity scoring for abnormal parameters was applied as described by Venkatapathiah et al. 8 (Table 1).
Severity Scoring for Abnormality Parameters.
Statistical Analysis
Data were analysed using IBM SPSS Statistics version 25.0. Continuous variables are presented as mean ± standard deviation (SD) or median (interquartile range, IQR) depending on distribution, and categorical variables as counts and percentages. Between-group comparisons were performed using Student’s t-test or Mann-Whitney U test for continuous data, and χ² or Fisher’s exact test for categorical data. Comparisons across more than two groups were performed using one-way ANOVA or Kruskal-Wallis test, followed by appropriate post hoc testing.
Spearman’s rank correlation coefficient was used to assess associations between nailfold capillaroscopic parameters and disease activity/severity scores (PASI in psoriasis; DAPSA in PsA). Missing data were not encountered in this study. The potential confounding effect of treatment (biologics vs. conventional therapy) was explored by subgroup analyses. No formal adjustment for multiple comparisons was applied, given the exploratory nature of the study; findings should be interpreted as hypothesis-generating. A P < .05 was considered statistically significant.
Results
The age range for patients with psoriasis ranged from 17 to 68 years, comprising 13 males (65%) and 7 females (35%). Meanwhile, patients with PsA ranged in age from 16 to 70 years, including 7 males (35%) and 13 females (65%). The control group ranged from 26 to 50 years, with 11 males (55%) and 9 females (45%).
The disease duration in the psoriasis group ranged from 1 to 30 years, while in the PsA group ranged from 1 to 25 years.
Among psoriasis patients, 10% received biological treatment, whereas 90% of cases were on methotrexate and or topical treatment. In the PsA group, 35% received biological while 65% of cases were treated with methotrexate. Coexistent nail psoriasis involvement was observed in 70% of patients in both the psoriasis and psoriatic arthritis groups.
The Psoriasis Area Severity Index (PASI) score in the psoriasis group ranged from 2.7 to 18.8, while in PsA patients it ranged from 2.6 to 19.
The DAPSA score ranged from 14 to 73, as shown in Table 2.
Comparison Between PsO and PsA Groups Regarding PASI and DAPSA Scores Among the Studied Patients.
In nail fold capillaroscopy, capillary density ranged from 5 to 9 capillaries/mm ( mean ± SD 6.5 ± 1.28) in the psoriasis group and from 5 to 8 capillaries/mm (mean 5.75 ± 0.85 ) in the PsA group. In the control group, capillary loop density ranged from 7 to 10 capillaries/mm ( mean ± SD 8.45 ±0.69), as shown in Table 3 and Figure 1.
Comparison Between PsO, PsA and Control Groups Regarding Nail Fold Capillaroscopic Parameters Among the Studied Subjects.
Showing Density Measurement in 1 mm (Seven Capillaries) (Mild Rarefaction), Length (DL1 372 µm, DL3 290 µm) in a 45-year-old Male Psoriatic Patient, His Left Ring Finger Quadrant 2 (By Magnification Power 200×).
No rarefaction was observed in the control group; only one psoriasis case and one PsA case showed no rarefaction. Mild rarefaction was seen in seven psoriasis cases and two PsA cases, while moderate rarefaction occurred in 12 and 17 cases, respectively (Table 3 and Figure 1).
In the psoriasis group mean capillary length ranged from 90 to 320 μm (mean ± SD 237.85 ± 55.67), and from 143 to 380 μm (mean ± SD 253.6 ± 70.03) in the PsA group. In the control group, mean capillary length ranged from 170 to 285 μm (mean ± SD 208.05 ± 26.88) (Table 3 and Figure 1).
Mild avascularity was observed in four psoriasis cases and five PsA cases. Moderate avascularity in six and three cases, respectively, while severe avascularity was detected in five psoriasis and seven psoriatic arthritis cases (Table 2 and Figure 2).
(A, B) Showing Avascular Areas (Mild Avascularity) (Yellow Arrows), (A) Low Density 5 Capillaries in 1 mm (Moderate Rarefaction) in a 30 Years Old Female Psoriatic Patient, Her Left Middle Finger Quadrant 3, (B) Showing Low Density 3 Capillaries in 1 mm (Severe Rarefaction) 44-year-old Male PsA Patient, His Right Ring Finger Quadrant 2 (By Magnification Power 200×).
Other nail fold capillaroscopic parameters, such as apical diameter, wide capillaries (by scoring), and arterial and venous limb diameters, were also assessed (Table 3 and Figure 3).
Showing Apical Diameter 26 µm (Black Arrow) (No Wide Capillaries, Only One Dilated Capillary) in a 38-year-old Female Psoriatic Patient, Her Right Middle Finger Quadrant 2 (By Magnification Power 200×).
Capillary tortuosity severity ranged from mild to severe, and neoangiogenesis was also observed in the examined cases, as shown in Table 4 and Figures 4 and 5.
Comparison Between PsO, PsA and Control Groups Regarding Other Nail Fold Capillaroscopic Parameters Among the Studied Subjects.
Showing Tortuous Vessels (Moderate Tortuosity) (Green Arrows) in a 35-year-old Male Psoriatic Arthritis Patient, His Right Ring Finger Quadrant 2 (By Magnification Power 200×).
Showing Tortuous Capillaries (Moderate) (Green Arrows) and Crossed Capillary (Black Arrow) in a 35-year-old Male Psoriatic Patient, His Left Little Finger (By Magnification Power 200×).
Capillary loop crossing (>10%) was observed in 40% of the psoriatic group (12 cases), 50% in the PsA group (13 cases), as shown in Table 4 and Figure 5.
Abnormal capillary shapes, including bushy capillaries (neoangiogenesis), were observed in 6 psoriasis cases (30%) and 13 psoriatic arthritis cases (65%), as shown in Table 4 and Figure 6.
Showing Neoangiogenesis (Bushy) Capillary (Green Arrow) in a 35-year-old Female Psoriatic Arthritis Patient, Her Right Index Finger Quadrant 4 (By Magnification Power 200×).
Bizarre abnormal shapes were observed in three cases (15%) of both psoriasis and PsA patients, as shown in Table 4 and Figure 7.
(A) 40-year-old Female Psoriatic Arthritis Patient, Her Left Middle Finger Quadrant 2, (B) 45-year-old Female Psoriatic Arthritis Patient, Her Left Little Index Finger Quadrant 3: Both Showing Bizarre Abnormal Shapes (Black Arrows) (By Magnification Power 200×).
The subpapillary venous plexus was visible in 45% of psoriasis patients, 70% of PsA patients and 40% of the control group. Haemorrhage on nail fold capillaroscopy was observed in 25% of psoriasis patients and 20% of PsA patients (Table 4 and Figure 8).
(A) Showing Subpapillary Venous Plexus (Green Arrow) in a 25-year-old Female Psoriatic Arthritis Patient, Her Left Middle Finger Quadrant 4, (B) Showing Haemorrhage (Severe Haemorrhage) (Blue Arrows (in a 29-year-old Female Psoriatic Patient, Her Right Middle Finger Quadrant 2 (By Magnification Power 200×).
Table 5 demonstrates a highly significant reduction in mean capillary loop density among psoriasis and PsA patients compared with the control group (P < .01).
A highly significant increase in the percentage of crossed capillary loops was also observed in both psoriasis and PsA groups (P < .01).
There was a significant increase in the presence of bushy capillaries among PsA patients compared with psoriasis patients (P < .05; Table 5).
Post Hoc Analysis and Multi-comparison Between Groups.
A statistically significant increase in capillary tortuosity percentage was found among psoriasis patients (P < .05), while among PsA patients showed a highly significant increase (P < .01), as shown in Table 5.
There was a statistically significant decrease in avascularity severity among PsA patients who were treated with biologic therapy (P < .05), as shown in Table 6.
Relation of Biological Treatment with Nail Fold Capillaroscopic Parameters Among PsA Group.
There was a highly significant increase in apical diameter among PsO and PsA patients with nail involvement (P < .01), as shown in Table 7.
Relation of Nail Affection with Nail Fold Capillaroscopic Parameters Among PsO and PsA Groups.
There was a statistically significant increase in avascularity severity, capillary tortuosity severity and tortuosity percentage among PsO and PsA patients with nail involvement (P < .05), as shown in Table 7.
Correlation analysis showed a highly significant positive correlation between PASI score and capillary tortuosity severity in the PsO group (P < .01), and a statistically significant positive correlation in the PsA group (P < .05), as shown in Table 8.
Correlation of PASI Score, DAPSA Score, with Nail Fold Capillaroscopy Severity Score Among PsO Group and PsA Group.
There was a statistically significant positive correlation between DAPSA score and apical diameter among PsA patients (P < .05), as shown in Table 8.
Discussion
PsA is a common progressive arthropathy in people with psoriasis. It can manifest clinically in a wide range of ways, from moderate to severe joint disease. To avoid long-term joint injury, functional impairment, and higher mortality, early diagnosis and treatment are crucial. 9
Our study demonstrated characteristic nailfold microvascular abnormalities in psoriasis and PsA, including capillary tortuosity, branching, enlarged apical diameter, and avascular areas. These findings support the concept that psoriatic disease is not confined to the skin and joints but reflects systemic microvascular involvement.
Previous studies have reported similar NFC abnormalities. Kamboj et al. 5 and Bardehle et al. 10 also described tortuous and bushy capillaries as frequent features in psoriatic patients, consistent with our findings. The capillary branching and tortuosity may be explained by the disruption of normal adhesion between endothelial cells and the papillary dermis matrix. 11
Elmesiry et al. 12 reported more frequent haemorrhages than observed in our study, which may be attributable to differences in disease severity or treatment exposure.
Our research showed a significant increase in capillary tortuosity and avascularity severity among cases (both PsO and PsA groups) with nail affection, which agrees with Bardehle et al. 10 and Ribeiro et al., 13 respectively. These findings could be explained by that nail disease may be a clinical marker of systemic microvascular damage.
Mechanistically, these abnormalities likely reflect the angiogenic and inflammatory milieu of psoriatic disease. Elevated levels of VEGF, TNF-α, and IL-17 promote pathological angiogenesis and vascular remodelling, 14 while chronic inflammation contributes to endothelial damage and capillary rarefaction. The presence of avascular areas in both psoriasis and PsA patients supports the concept of progressive microvascular dropout in chronic disease. 15
The observation that biologic therapy was associated with less severe avascularity is clinically relevant, and this agrees with Anghel et al. 16 It suggests that effective systemic treatment may partially reverse or prevent microvascular damage. This highlights the potential utility of NFC as a tool for monitoring treatment response and systemic vascular involvement.
In the present study, there was a highly significant positive correlation of DAPSA score with apical diameter among the PsA group, which is in accordance with Fukasawa et al. 17
In our study, there was a severity scoring for nail fold capillaroscopy regarding (rarefaction, haemorrhage, wide capillaries, elongation and avascularity) among psoriatic and PsA, which showed a significant positive correlation between PASI score and capillary tortuosity severity scoring among our patients’ groups.
Limitation
It was better to choose newly diagnosed patients, but unfortunately, our patients were on medical treatment, DMARDs and biologicals.
The cross-sectional design precludes assessment of longitudinal changes and causality. Although all NFC examinations were performed by a single trained investigator to reduce variability, this also introduces potential observer bias, and inter-observer reliability was not assessed.
A small number of patients participated in our study, so large-scale studies are needed to detect other correlations with disease severity or any specific changes which may help in early detection of PsA.
Although matching was attempted, the PsO group showed male predominance while the PsA group showed female predominance, reflecting clinic recruitment patterns.
Recommendations
From the results of this study, we recommend that:
Application of NFC in psoriatic and PsA patients before starting treatment, and also in follow-up of treatment and in patients with different biological treatments. Application of NFC in a greater number of patients with different types of skin psoriasis and different patterns of arthropathy. NFC in correlation to inflammatory cytokines as TNF-α, IL-17 and IL-23 and activity markers like ESR, CRP and VEGF. Studies are needed to assess the difference between nail fold capillaroscopic changes in psoriatic patients with and without comorbidities like cardiac affection.
Conclusion
NFC may provide insights into systemic microvascular invol-vement and disease activity; however, longitudinal validation is required before it can be considered a monitoring tool.
Footnotes
Data Availability Statement
Data are available upon reasonable request from the editor-in-chief.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
Ethical Approval and Informed Consent Statements
Approval to participate study was approved from the Research Ethics Committee at the Faculty of Medicine, Ain Shams University (No. FWA000017585). Written informed consent was obtained from all participants after being fully informed about the purpose, procedures, and benefits of the study.
Funding
The authors received no financial support for the research, authorship and/or publication of this article.