A Relationship Between Extracapsular Involvement And Response To Steroid Treatment In Polymyalgia Rheumatica: Too Soon To Conclude?

We read with great interest a recent paper by Mackie et al .1 The authors found that an extracapsular pattern of inflammatory involvement on whole-body, multiple-joint MRI was associated with complete glucocorticoid response, higher pretreatment C-reactive protein and serum interleukin-6.We commend the authors for studying such a challenging disease with advanced imaging and linking it to treatment response. However, we have several concerns. First, it is unclear what criteria were used to distinguish an MRI of ‘extracapsular pattern’ from that of ‘non-extracapsular pattern’. Since at least eight large joints were evaluated bilaterally, are there patients with an extracapsular pattern in certain joints but not in others? …