Background Early diagnosis of psoriatic arthritis (PsA) is a challenging topic. PsA is not a mild disease. Untreated it is to compare with rheumatoid arthritis. PsA leads in a high percentage to joint damage, to a poor functional status and to a reduced quality of life. Due to cardiovascular complications patients with PsA die earlier than the general population. Today effective treatment can be started earlier but early diagnosis is still a big problem.We have classification criteria (Caspar, Gepard) and the enthesitis-synovial concept is part oft he international ASAS classification criteria, but we have no early- disease-diagnostic criteria. The fact that skin lesions normally precedes the manifestation of PsA (80%) makes the cooperation between dermatologists and rheumatologists crucial.

Objectives Our hypothesis is that tendonitis and enthesitis of the feet and capillary abnormalities in early PsA can be diagnosed in a very early stage of the disease long before joints involvement is occurring.

Methods We investigated 51 consecutive patients with psoriasis diagnosed and referred by the collaborating dermatologists, without joint problems. Psoriasis must be diagnosed for the first time and should not last longer than 2 years. (All dermatologists in the area participated). No specific dermatological treatment should be started except topics. We performed PW-doppler ultrasound examination of the peronaeus tendons, the tibialis posterior muscle tendons, the tibialis anterior tendons and the attachement oft he Achillles tendons on both sides as well as nailfold capillaroscopy oft he 2.-4.finger of the right hand. A control group of 10 healthy controls was examined.

Results Demographic data and specific assessments (Caspar, Gepard, PASI, DLQI, DAS28) were obtained from the psoriasis group. 20% of the study group had a nail psoriasis, more than 50% were suffering from psoriasis capitis. Our data reveal a large number of grade 1 (75%) and 2 (35%) (range grade1–3) tendonitis abnormalities in the peronaeus- and tib. posterior tendons. Joint effusions could be mostly seen in the talo-tibial joint, whereas the Achilles tendons and the bursa achillea were not often affected. Capillaroskopy results showed torsions/twist-signs in 18% in psoriasis- patients/nail psoriasis -patients which did not differ from the results of the control group. Hair-Pin capillaries occurred significantly more often in the control-group. No dactylitis could be detected in these early cases.

Conclusions Tendonitis of the foot-ankle region occurs strikingly more often than expected in early stages of psoriasis. Ultrasonic of the ankle region is easy to perform in rheumatologic practises. Capillaroscopy is more time consuming and should be reserved for special diagnostic questions.

We have a simple tool to modify the natural course of PsA by early diagnosis. But that works only in a tight interdisciplinary setting (tight junction) between rheumatologists and dermatologists.

Acknowledgement The study was supported by a research grant from Pfizer

Disclosure of Interest D. Becker-Capeller Grant/research support from: Pfizer Research Support, S. El-Nawab-Becker: None declared, C. Iking-Konert: None declared