The distribution of pulmonary shadowing in farmer's lung.

Reports of the radiological features in farmer's lung are inconsistent. We have reviewed clinical and radiological findings in eight patients with farmer's lung in the acute and sub-acute phases. In the acute phase the main feature is transient widespread diffuse shadowing of air space consolidation. In the sub-acute phase, the predominant feature is fine nodular shadowing tending to involve either the upper half or upper two-thirds of the lungs with relative sparing of the basal segments. This is in accordance with both the pathophysiological behaviour of the inhaled particulate antigen and the subsequent distribution of pulmonary changes in chronic farmer's lung.