Psoriasis and systemic inflammation: underdiagnosed enthesopathy

Abstract

Our understanding of the pathogenesis of psoriasis is changing rapidly and the traditional view that it is a disease limited to the skin continues to be challenged. Indeed, there is convincing evidence that psoriasis patients have a higher prevalence of comorbid disease, particularly cardio-metabolic disorders and psoriatic arthritis (PsA). The results of recent investigations into psoriasis and cardiovascular or metabolic comorbidities provide increasing evidence for a possible shared pathogenic mechanism for these disorders, linked by an underlying chronic systemic inflammatory state. This highlights the importance of investigating associated comorbidities beyond skin manifestations. Psoriatic arthritis is a chronic inflammatory arthropathy that can occur in association with psoriasis and most commonly affects the distal joints in the hands and feet. Skin lesions precede arthritic symptoms in approximately 75% of cases; typically, the cutaneous manifestations of the disease develop 10 years prior to the onset of joint symptoms. This disease course, therefore, provides a potential window of opportunity to initiate effective and aggressive therapies to prevent long-term damage, if symptoms of PsA can be detected early. One of the major features of PsA is enthesitis, yet clinically asymptomatic cases of entheseal abnormalities are likely to go undiagnosed. This concept was evaluated in a prospective study in which entheseal changes in clinically asymptomatic psoriasis patients were compared with findings from a control group. Ultrasonography detected a significantly higher incidence of entheseal abnormalities in patients with psoriasis, despite the absence of clinical symptoms of arthropathy. Ongoing monitoring of these patients has also revealed that a higher baseline score for enthesitis may be associated with a more severe psoriasis outcome. These findings demonstrate that detecting early signs of PsA in asymptomatic patients with psoriasis may have the potential to positively influence disease prognosis and ultimately clinical outcome. Dermatologists can, therefore, play a key role in the early detection and management of PsA.