In psoriatic arthritis, swelling and pitting oedema may be caused by diVerent pathogenic mechanisms: on one hand, the involvement of tenosynovial structures; on the other hand, the involvement of lymphatic vessels, which may be rarely implicated by the inXammatory process. This diVerent involvement is responsible for a diVerent response to therapy and a diVerent clinical outcome. In fact, patients with inXammation of the tenosynovial structures and normal lymphatic drainage have a more favourable clinical outcome and response to pharmacologic treatment, whilst patients aVected by psoriatic arthritis with chronic lymphatic vascular damage are characterized usually by resistance of oedema to therapy. In this study, we report two cases of psoriatic arthritis with distal extremity swelling and pitting oedema. In the Wrst patient, the swelling and pitting oedema were associated with lymphatic obstruction, as detected by lymphoscintigraphy. In the second, the predominant involvement of the tenosynovial structures, as shown by magnetic resonance, with normal lymphatic Xow, may have been the cause of arthritis with oedema. These diVerent pathogenetic mechanisms were associated with diVerent response to therapy. Nevertheless, oedema was resistant to therapy in both patients probably because of other unknown factors, which inXuence therapy and clinical outcome.