In the past decade, a vigorous debate has erupted over the existence or non-existence of the diagnosis polymyositis (PM).1 It is commonly accepted that the current PM diagnosis probably covers several different forms of immune mediated myopathies, including necrotising myopathies and myopathies associated with certain myositis specific autoantibodies.

In this issue, Nozaki and Pestronk2 add another branch to the PM tree (see page 904).2 In their paper, 12 patients are described who all had muscle complaints, a normal level of serum creatine kinase (CK) and elevated levels of serum …