Organizing pneumonia: a kaleidoscope of concepts and morphologies

The basic histopathological pattern of organizing pneumonia (OP) is well recognized, but the contexts in which it is encountered continue to increase. In parallel with an appreciation of new causes and associations of OP, an understanding of OP in the spectrum of lung injury and repair has evolved. There is an increasing array of HRCT manifestations of OP, some of which have only recently been described. This article concentrates on new concepts surrounding OP and highlights newly described imaging patterns.