Distal extremity swelling with pitting edema in psoriatic arthritis: evidence of 2 pathological mechanisms.

Distal extremity swelling with pitting edema due to altered lymphatic drainage has been reported in some patients with psoriatic arthritis (PsA). The edema usually affected the upper limbs in an asymmetric pattern and was resistant to therapy. We describe 2 additional cases. The distal swelling and pitting edema responded promptly and completely to corticosteroids in the first patient but persisted in the second. Lymphoscintigraphy and magnetic resonance imaging (MRI) revealed a predominant tenosynovitis in the hand without lymphedema in the first patient, and impaired lymphatic drainage without tenosynovial sheath involvement in the second. We conclude that 2 different mechanisms, characterized by a different response to therapy, may be associated with the same clinical picture of distal swelling with pitting edema in patients with psoriatic arthritis. Lymphoscintigraphy and MRI are useful in defining the structures involved and in predicting the prognosis.