Nail psoriasis represents an important feature of psoriasis and psoriatic arthritis patients. In psoriasis patients, nail involvement represents a risk factor for psoriatic arthritis. Moreover, nail psoriasis was associated with distal interphalangeal joint arthritis. It is also one of the CASPAR classification criteria for psoriatic arthritis.
The complex anatomy of the nail, including the enthesis complex, makes the clinical assessment difficult, as well as the accurate description of the pathology for each structure.
Studies have shown a link between nail, extensor tendon enthesis and DIP joints involvement in psoriatic and psoriatic arthritis patients.
Ultrasound of the nail includes the evaluation of nail plate, nail bed, and extensor tendon enthesis.
Ultrasound of the normal nail plate shows a trilaminar structure: two hyperechoic lines, the ventral and dorsal, separated by a hypoechoic line. The nail bed appears like a hypoechoic band, between the ventral plate and the bone. Some Doppler signals may be seen in the normal nail bed.
In early nail involvement, irregularities and loss of sharpness of the dorsal plate can be seen. As the disease progresses, loss of sharpness of ventral plate and loss of trilaminar structure can be seen.
In the nail bed involvement, the distance between the ventral plate and the bone can be increased. Also, an increase of Doppler signal has been reported.
Compared to rheumatoid arthritis patients, different patterns of both nail plate and nail bed involvement have been seen in psoriatic arthritis patients.
Disclosure of Interest None declared