Psoriasis: skin and joints, same fight?

Psoriasis is a multifactorial disease, its pathogenesis combining hereditary and environmental factors. This affliction is characterized by a large polymorphism of cutaneous lesions, but also by its association with inflammatory articular manifestations which are by far the most frequent extra-cutaneous complication. Although the link between cutaneous lesions and articular manifestations remains for a large part a mystery, recent advances in immunopathology now permit a better understanding of certain similarities and differences. To analyse more precisely the differences and similarities between psoriasis and psoriatic arthritis, it is of interest to study successively: • epidemiological and genetic data; • animal models; • immunohistochemical study; • arguments derived from the use of new immunomodulatory biomedicines. Psoriatic arthritis is not a synovial form of psoriasis, as evidenced by genetic and immune differences. The specific determinants that favour the appearance of articular symptoms are yet to be more precisely identified, even in patients displaying minimal cutaneous lesions.