Nail Ultrasound in Psoriasis and Psoriatic Arthritis—A Narrative Review

Abstract

Ultrasonography has advantages for assessing psoriatic arthritis (PsA) due to its ability to evaluate several targets, including joints, entheses, and tendons, but also skin and nails. Although ultrasound is widely used in PsA, nail ultrasound, despite its potential as a non-invasive method for the early detection of inflammation in the nail apparatus, has low applicability in medical practice, as probes with a higher frequency are needed compared with the frequency of probes usually used. In the present article, we have narratively evaluated the studies published in the last 5 years (19 February 2018–18 February 2023) on nail ultrasound value in the diagnosis and monitoring of PsA. The studies published during this period share common measurement parameters, such as the OMERACT definition of enthesis published in 2018. We included original articles published in PubMed and Web of Science using the following search terms in all possible combinations: psoriatic arthritis, psoriasis, ultrasound, and nail. Articles were declared relevant if they presented data on nail morphology, power Doppler evaluation and nearby structure evaluation, while focusing on digitorum extensor enthesitis. In most of the studies, common morphological parameters were generally increased in patients with psoriasis or PsA and were demonstrated to change with medication. The thickness of the extensor tendon was greater in patients with PsA and psoriasis versus controls and it was correlated with nail clinical changes, especially the presence of onycholysis. The presence of PD showed large variability in healthy individuals. The link between enthesitis and nail involvement is still a subject of controversy, taking into account the latest histological findings. The use of ultrasound in the evaluation of nail and DIP enthesitis remains a challenge and an area of research in the coming years.

Ultrasonographic and power doppler parameters of nails fail to differentiate between onychodystrophy in patients with psoriasis vulgaris or psoriatic arthritis

“…Patients with visible nail disease (groups 2 and 4) displayed a more pronounced loss of the trilaminar pattern compared to groups without nail disease (groups 1 and 3). Increased nail bed thickness is considered an early indicator of psoriatic nail disease, [14][15] a correlation supported by our study when correlating NAPSI with mean nail bed thickness (p = 0.0072) from the Spearman test (Table 1). However, when comparing groups with nail disease, including the patients with psoriasis and arthritis, no significant differences were noted concerning gray scale measurements.…”

Assessment and Monitoring of Nail Psoriasis with Ultra-High Frequency Ultrasound: Preliminary Results

“…The cuticle appeared as a proximally localized structure with echogenicity comparable to that of the ventral and dorsal lamina [ 24 ]. US changes of the nail plate in a patient with psoriatic onychopathy were detectable by a loss of echogenicity of the ventral plate in the early stage, and the involvement of the dorsal lamina with a complete loss of the trilaminar aspect in the advanced stages [ 25 ]. The qualitative severity of psoriatic nail alteration could be assessed ultrasonographically according to the classification presented by Wortsman et al: type I was defined as focal, point-like hyperechoic involvement of the ventral plate; type II as continuous loss of the borders of the ventral plate; type III as the identification of wavy plates; and type IV as the complete loss of definition of both plates [ 26 ].…”

“…Another study identified nail bed thickness above 2.0 mm as a cut-off point for the diagnosis of psoriatic changes [ 30 ]. In more advanced stages, an increase in the distance between the ventral plate and the bony margin of the distal phalanx (>2.5 mm) was detectable [ 25 ]. Gisondi et al in 2012 identified a mean thumbnail bed thickness of 2.95 mm in a population of patients with psoriatic onychopathy and a mean NAPSI of 18 [ 28 ].…”