Plant-thorn synovitis occurring in a child with psoriatic arthritis

In psoriatic arthritis, trauma to joints may be important in determining the site of joint involvement. We describe a child with a psoriatic arthritis in whom penetrating injury with a rose thorn led to a localized chronic synovitis which could not be distinguished clinically from psoriatic arthritis but which was effectively treated by synovectomy and removal of the remaining thorn.