OBJECTIVE

To explore potential subclinical involvement of the axial skeleton by MRI of the sacroiliac joints (SIJ) and entire spine in patients with skin psoriasis without clinical evidence of peripheral or axial inflammation.

METHODS

Twenty patients with skin psoriasis but no clinical evidence of peripheral or axial inflammation and 22 healthy controls underwent standardized dermatologic and rheumatologic clinical examination and unenhanced 1.5T MRI of the SIJ and the entire spine. Two blinded readers globally assessed the presence or absence of SIJ inflammation simultaneously on T1-weighted and STIR MRI sequences with a confidence estimate. Bone marrow edema, fat metaplasia, erosion and ankylosis of the SIJ, and vertebral corner inflammatory and fat lesions were recorded using standardized modules. The prevalence of each lesion type was calculated in both groups averaged across 2 readers. The number of subjects with ≥1/2/3/4/5 lesions in the SIJ and spine as concordantly assessed by both readers was recorded.

RESULTS

Median duration of skin psoriasis was 23.0 years, median age of patients 48.5 years. 25.0% of patients and 9.1% of healthy controls were concordantly classified by both readers as having SIJ inflammation (p=0.23). Prevalence of bone marrow edema and structural lesions was comparable across patients and controls both on SIJ and spine MRI.

CONCLUSIONS

In this controlled study, patients with skin psoriasis, but no clinical arthritis or spondylitis showed limited evidence of concomitant subclinical axial involvement by SIJ and spine MRI. These findings do not support routine screening for subclinical axial inflammation in patients with longstanding skin psoriasis. This article is protected by copyright. All rights reserved.