Detection of asymptomatic enthesitis in psoriasis patients: An onset of psoriatic arthritis?

Presence of asymptomatic joint involvement is recognized in patients with psoriasis. However, it remains elusive whether such patients develop psoriatic arthritis (PsA). The aim of the present study was to examine the incidence of asymptomatic joint lesions, in particular, enthesitis in patients with psoriasis vulgaris (PsV) and to further assess the clinical features. Eighteen PsV and 28 PsA patients were enrolled for examination by positron emission tomography/computed tomography (PET/CT) using (18) F-fluorodeoxyglucose (FDG). Any nail, scalp and intergluteal involvements were reported. Levels of serum C-reactive protein (CRP), white blood cell (WBC) counts and erythrocyte sedimentation rate (ESR) were examined. All of the PsA patients showed FDG accumulation in the affected joints. Notably, asymptomatic enthesitis was detected in six out of 18 PsV patients (33%), and they were diagnosed as having subclinical PsA. Incidences of scalp, intergluteal and nail psoriasis in subclinical PsA patients were 100%, 83% and 64%, respectively, which were higher than those in PsV patients (67%, 25% and 40%, respectively). CRP, WBC counts and ESR were invariable between PsV and subclinical PsA groups. PET/CT imaging could discover asymptomatic enthesitis. Our data suggested that the subpopulation of subclinical PsA was much higher than expected. Higher prevalence of nail, scalp and intergluteal psoriasis confirmed the risk of PsA as previously described.