Nail affection as a central part of the entheseal organ in psoriasis patients for early detection of psoriatic arthritis

• Main Author: Reem ElMallah
• Format: Article
• Language: English
• Published: Elsevier 2020-10-01
• Series: Egyptian Rheumatologist
• Subjects: Psoriasis; Psoriatic arthritis; Musculoskeletal ultrasound; Nail; Enthesitis
• Online Access: http://www.sciencedirect.com/science/article/pii/S1110116420300831

Aim of the work: To evaluate nail unit and detect subclinical enthesitis at extensor tendons in psoriatic patients for early detection of psoriatic arthritis (PsA). Patients and methods: The study included 60 PsO patients and 60 matched healthy controls. Patients underwent history, clinical examination, assessment of Psoriasis Area and Severity Index (PASI), Nail Psoriasis Severity Index (NAPSI), Leeds Enthesitis Index (LEI), musculoskeletal ultrasound (MSUS) both grey and power Doppler (PD) for measuring nail bed thickness (NBT), nail vessels resistive index (NVRI), extensor digitorum tendon insertion for enthesitis and distal interphalangeal joints for synovitis. Results: Patients were 38 females and 22 males (F:M 1.7:1) with mean age 45.1 ± 13.5 years. Nail irregularities were in all cases. The mean NBT of right thumb and index were significantly increased in patients (2.3 ± 0.6 and 1.9 ± 0.4) compared to control (1.5 ± 0.2 and 1.2 ± 0.2; p < 0.001 respectively). The mean NVRI was significantly increased (0.7 ± 0.1) in cases compared to control (0.4 ± 0.1; p < 0.001). NBT > 1.8 mm would differentiate cases from control (sensitivity 76.7% and specificity 100%). Frequency of tendons hypoechogenicity and thickness were significantly increased (73% and 93.3%) in patients. A significant correlation was found between disease duration and NAPSI (r = 0.4, p = 0.04). Enthesophyte with PD significantly correlated with PASI (r = 0.6, p = 0.02). Enthesophyte without PD significantly correlated with PASI (r = 0.6, p = 0.001) and with tendon thickness (r = 0.5, p = 0.01). A significant correlation was found between NBT and LEI (r = 0.7, p = 0.01). Conclusion: MSUS is an important tool for examining nail as part of the entheses in psoriasis. There is a significantly increased frequency of extensor tendon enthesopathy in fingers with involved nails.