Clinical and dermoscopic evaluation of nail findings of rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis patients and comparison with psoriasi̇s patients

Introduction: Psoriasis is a chronic inflammatory disease caused by an immune-mediated mechanism (IMID group) and psoriatic arthritis is the most common comorbidity of psoriasis. Rheumatoid arthritis (RA) and Ankylosing Spondylitis (AS) are also included in the IMID group diseases and have clinical similarities with psoriatic arthritis. Nail involvement is particularly important for psoriasis and psoriatic arthritis. As the nail is seen as an end part of the joint system, it has been thought that nail lesions can also be seen in RA and AS. Here, we aimed to investigate nail changes in RA and AS patients and compare them with the nail findings of psoriasis and psoriatic arthritis patients. Materials and Methods: The study included 25 PsO and 25 PsA patients who applied to the Bezmialem Vakıf University Dermatology outpatient clinic and 25 rheumatoid arthritis and 25 ankylosing spondylitis patients who applied to the Physical Therapy and Rehabilitation outpatient clinic between 1.11.2020 and 1.11.2021. Patients' fingernails were examined, and dermoscopic images of the two nails on each hand were recorded. Demographic and clinical characteristics of the patients, as well as visible and dermoscopic nail findings were recorded. Results: Thirty-five of the patients were male and 65 were female. The mean age was 43.59 ±12.69 years. There was no difference in the mean of PASI and NAPSI between PsO and PsA patients (p=0.382, p=0.734, respectively). In psoriasis patients, NAPSI score had correlation with disease duration (p=0.02). The most common nail findings were onycholysis (88%, n=22) and pitting (88%, n=22) in PsO patients and also in PsA patients (onycholysis: 88%, n=22; pitting: 80%, n=20). In the ankylosing spondylitis group (56%, n=14) the most common nail finding was leukonychia, while the most common nail finding in the rheumatoid arthritis group (48%, n=12) was vertical striae-trachinochia. There was no statistically significant difference between the groups in leukonychia and horizontal (transverse) depressions in the nail plate (p= 0.56, p=0.05, respectively). In dermoscopy; multi-row capillary vascularization was common in the proximal nail fold in patients with Ps, PsA, RA, and AS. Megacapillary (32%, n=8), microhemorrhagic dots (32%, n=8), overlapping vessels (48%, n=12) were most common in patients with ankylosing spondylitis; distorted, branched, purple vessels were most common in patients with rheumatoid arthritis (20%, n=5). Psoriasis patients (Ps:76, n=; PsA: 84%, n=21) had more clustered dotted vessels (p<0.001), while patients with rheumatoid patients (64%, n=6) had more parallel dotted/short linear vessels ('Fish school-like" vascular pattern) (p=0.01). Also, pseudofiber sign was mostly seen in PsA patients (p=0.04). Conclusion: Nail findings can be seen in IMID group diseases due to inflammation and vascular changes in the pathogenesis. However, nail findings were not as rich in RA and AS patients as in psoriasis patients. While pitting, onycholysis, splinter hemorrhage and subungual hyperkeratosis were common in psoriasis nails; leukonychia and horizontal depressions were not found to be specific to the disease. Also, sparsely clustered dotted vessels in the proximal nail fold suggest psoriasis nail and parallel clustered, short linear vessels and irregular, branched, purplish vessels may suggest RA nail. As a result; dermatological examination, detailed nail examination and nail dermoscopy are important in the differential diagnosis of IMID group diseases, especially in the early stages.