The problem in differentiation between psoriatic-related polyenthesitis and fibromyalgia

The recognition of the primacy of enthesitis in animal models of spondyloarthritis and the prevalence of clinically occult enthesopathy in psoriatic subjects and of persistent joint pain in PsA subjects who have ostensibly good reduction of joint swelling under biological therapy has highlighted the potential impact of polyenthesitis in psoriatic disease. In daily practice, the formal demonstration of enthesitis is challenging for the following reasons: the relatively avascular nature of enthesis, often leading to the absence of overt clinical inflammatory signs; the frequent lack of elevation of inflammatory markers; and finally, the limitations of current imaging techniques to provide supportive evidence for inflammation in these areas. Consequently, enthesitis may present as widespread pain indistinguishable from FM or may emerge as the dominant feature after successful biological therapy for suppression of synovitis. The unmet needs in the differentiation between FM and enthesitis in psoriatic disease patients are highlighted and critically evaluated in this article.