How do you differentiate between axial psoriatic arthritis and axial spondylitis with psoriasis, and is it important to distinguish between these two conditions from a prognostic and treatment perspective?  

This is an ongoing controversy in the field(s), with some studies suggesting that clinical differences allow differentiation of axial involvement in psoriatic arthritis from classical ankylosing spondylitis. The concept was recently the topic of a study by Feld and colleagues published in Rheumatolo...