Magnetic resonance imaging (MRI) of feet demonstrates subclinical inflammatory joint disease in cutaneous psoriasis patients without clinical arthritis.

We evaluated inflammation at the small joints of feet in psoriasis patients without clinical arthritis (PsO) as against clinically overt psoriatic arthritis (PsA) patients, using a low field magnet extremity MRI (eMRI). Patients with psoriasis recruited from dermatology and rheumatology clinics of a tertiary care institution in southern India were divided into PsO and PsA groups. Demographic and physical examination details were recorded. Consenting patients underwent non-contrast eMRI of the right foot. Two trained readers scored the MRI parameters of inflammation (synovitis, tenosynovitis, osteitis) using a modification of the PsA magnetic resonance imaging score (PsAMRIS). Proportion of patients with any sign of MRI inflammation was noted. Clinical variables were compared with inflammation scores for any association. A total of 83 patients (30 PsA and 53 PsO), with 75% males and mean age of 42.2 ± 11.6 years were included. There was no statistical difference between the median eMRI inflammatory scores in PsA and PsO patients (p = 0.493). Evidence of inflammation was present in 33.9% and 50% patients in the PsO and PsA groups, respectively. Early arthritis for psoriatic patients screening questionnaire (EARP) score of ≥ 3 was significantly associated with imaging features of inflammation in PsO group (p = 0.044). This study corroborates a high proportion of subclinical inflammation in small joints of foot in PsO patients, which needs to be reproduced in larger, longitudinal cohorts to predict risk factors for progression to future PsA development.