Nailfold capillary abnormalities: a possible cause for nail psoriasis?

Nailfold capillaroscopy as diagnostic test in patients with psoriasis and psoriatic arthritis: A systematic review

Up to 30 % of patients with psoriasis (PsO) develop psoriatic arthritis (PsA), and diagnosis can be difficult. Nailfold capillaroscopy (NC) is an easily applicable, non-invasive procedure to assess skin microcirculation. This systematic review investigates NC as diagnostic tool for PsO and PsA, including correlations between NC outcome measures to clinical and laboratory outcome measures. This systematic review was built on the PICO and PRISMA guidelines. In total 22 relevant studies were found Searching in the Web of Science, PubMed and Embase, latest update June 13th, 2022. The following NC outcome measures are found to be significantly more prevalent in PsO patients than healthy controls: reduced density, reduced length and more abnormal morphology. Likewise, in PsA patients, reduced density, more abnormal morphology, more microhaemorrhages and fewer hairpin shapes are found to be significantly more prevalent. Results were non-conclusive in terms of disease activity and duration with NC findings. Random-effects meta-analysis showed a significant reduction of density in PsO patients compared to healthy controls (studies: 6, n = 249; SMD = -0.91; 95 % CI [-1.41, -0.40], p = 0.0058, heterogeneity I²=74 %, AUC = 0.740) and in PsA patients compared to healthy controls (studies: 5, n = 130; SMD = -1.22; 95 % CI [-2.38, -0.06], p = 0.0432, heterogeneity I²=89 %, AUC = 0.806). No NC outcome measures were overall conclusive in differentiating PsO from PsA. Considering the conflicting results and small sample sizes further large-scale research on the identification of capillaroscopic changes in PsO and PsA and correlations with standardised clinical and laboratory outcome measures are necessary.

Novel application of optical coherence tomography and capillaroscopy in psoriatic arthritis in relationship to psoriasis and hand osteoarthritis

Objectives

Nailfold video capillaroscopy (NVC) and angiographic optical coherence tomography (OCTA) have potential in diagnosing PsA and differentiating it from psoriasis vulgaris (PsO) and hand OA. We aimed to assess the diagnostic properties of NVC and OCTA in patients with PsA compared with patients with PsO and hand OA based on nailfold capillary patterns.

Methods

Patients with DIP joint PsA and nail involvement (n = 50), PsO with nail involvement (n = 12) and OA (n = 13) were included in this cross-sectional study. Capillaries were evaluated semi-quantitatively and qualitatively. Differences in capillary findings between groups were assessed using mixed linear models. Binary logistic regression analyses were performed to determine the probability for PsA diagnosis based on capillaroscopy findings.

Results

Below mean capillary density and reduced nailfold blood flow in OCTA images distinguished PsA from both PsO (P = 0.004 and P = 0.052, respectively) and OA (P = 0.024 and P < 0.001, respectively). Qualitative analysis revealed that glomerular capillaries were found in only 3% of PsA patients but in 13% of PsO patients (P = 0.003). Furthermore, crossed vessels were seen in only 55% of PsA patients and 71% of PsO patients (P = 0.043). NVC microhaemorrhage was dominant in PsA patients (13%) and significantly different from OA patients (P <0.05). No capillary pattern was associated with an increased probability of the PsA diagnosis.

Conclusion

A pathognomonic pattern for PsA diagnosis was not identified; however, we demonstrated some characteristic capillaroscopy findings for PsA, such as decreased capillary density, reduced blood flow and fewer crossed vessels in OCTA and presence of NVC microhaemorrhages.

Dermoscopic features of nail psoriasis: Positive correlation with the severity of psoriasis

Dermoscopy is an efficient and non-invasive technique which has been widely used in the diagnosis of nail disorders including nail psoriasis (NP). Many nail dermoscopic features are considered as clues to NP. The aim of this study was to investigate specific dermoscopic features of fingernail psoriasis and the correlation between the severity of nail lesions or systemic inflammation, and psoriasis severity of skin and nail. This observational study recruited 135 patients with fingernail psoriasis (1186 fingernails) and 30 patients with onychomycosis (80 fingernails). All of the involved fingernails were examined with a handheld dermatoscope. The Nail Psoriasis Severity Index score (NAPSI) score, Psoriasis Area and Severity Index (PASI) score, body surface area (BSA), and detailed history of patients with psoriasis were recorded. Mann-Whitney U-test, χ² -test, Spearman's correlation, and Kruskal-Wallis H-test were used for statistical analysis, and the significance threshold was p < 0.05. The trial registration number was 2020-SR-045. We identified onycholysis as the most common feature (93.3%) of fingernail psoriasis. Red lunula, longitudinal fissures, transverse grooves, nail plate crumbling, trachyonychia, oil-dropping sign, erythematous border of an onycholytic area, subungual hyperkeratosis, and dilated streaky capillaries were relevant to NP severity (p < 0.05). Red lunula, transverse grooves, nail plate crumbling, trachyonychia, oil-dropping sign, erythematous border of an onycholytic area, splinter hemorrhages, and dilated streaky capillaries were relevant to systemic inflammation severity (p < 0.05). The total NAPSI score was positively associated with the PASI score and BSA (p < 0.0001). The thumb had a higher NAPSI score than the other fingers (p < 0.05). In conclusion, dermoscopic features can improve the accuracy of diagnosis of nail psoriasis, and have correlations with psoriasis severity.