Is it skin psoriasis or psoriatic arthritis?

A small study shows that ultrasound may be a viable diagnostic tool to determine whether patients have psoriasis or psoriatic arthritis, Italian researchers report.

For some patients with psoriasis, inflammation can extend beyond the usual skin flare-ups. It can also affect tendons and bones sometimes leading to structural abnormalities, such as thickening of tendons at the insertion site. This abnormality can be detectable by ultrasound which can confirm a diagnosis of psoriatic arthritis, or not.

In this study, published online March 16 in the Indian Journal of Dermatology, Venereology and Leprology, Italian researchers measured enthesis thickness by ultrasound of patients with psoriatic arthritis, skin psoriasis only and healthy controls.

Noteworthy differences in enthesis thickness between skin psoriasis and psoriatic arthritis patients were identified along the olecranon tuberosity, superior pole of the patella, and medial epicondyle of femur.

In other cases, the medial collateral ligament at the site of the femoral origin, was thicker for psoriatic arthritis patients, but not skin psoriasis patients or healthy controls. The most severe of connective tissue thickening occurred in cases where there was bone erosion.

Ultrasound scans were conducted to measure enthesis thickness, bone erosions, enthesis calcifications (enthesophytes), presence of blood flow, and the presence of bursitis. “The score, obtained by adding the thickness of all the eight examined entheses for each patient, showed significant differences among the three groups (psoriatic arthritis: 81.3; only skin psoriasis 74.4; Controls: 67.6; P < 0.0001),” researchers wrote.

“Our data demonstrated that the ultrasound measurement of the enthesis thickness enables a distinction between patients with psoriatic arthritis from those with only skin psoriasis. It is a useful method to improve diagnostic accuracy, especially in patients without clear clinical signs of enthesitis,” researchers wrote.

REFERENENCE

Graceffa D, Bonifati C, Lora V, et al. “Ultrasound assessment of enthesis thickness in psoriasis and psoriatic arthritis: A cross-sectional study,” Indian Journal of Dermatology, Venereology and Leprology, March 16, 2018. DOI:10.4103/ijdvl.IJDVL_205_17.