<prompt> Cryptogenic organising pneumonia Is characterised by all of the following exceptMigratory pulmonary opacitiesObstructive pattern of pulmonary functionAerial hypoxemiaGood response to coicosteroids  <response>: In cryptogenic organizing pneumonia,pulmonary function is impaired with a restrictive defect and aerial hypoxaemia,being most common.Chest X ray shows bilateral,patchydiffuse,recurrent migratory pulmonary opacities.These changes are more frequent in the periphery of the lung and in the lower lung zone.Glucocoicoid therapy induces clinical recovery in two-thirds of patients. Reference:Harrisons medicine-18th edition,page no:2166,2167. 