Histopathology of the Effect of Cortisone on the Irradiated Rat Lung

¹ The Radiological Laboratory, Department of Radiology, University of California School of Medicine, San Francisco., Major, MC, USA, at Fourth U. S. Army Medical Laboratory, Fort Sam Houston, Texas.
² The Radiological Laboratory, Department of Radiology, University of California School of Medicine, San Francisco.

The radiation reaction in the rat lung produced by a single exposure (3000 r) to the right hemithorax was characterized 90 days after irradiation by atelectasis, extensive or diffuse fibrosis, frequent infection, metaplasia, and occluded bronchi.

The irradiated lung responded to cortisone treatment in two ways: there were degrees of reaction varying from well-aerated to completely atelectatic lungs.

The most interesting finding was that the atelectasis in irradiated, non-cortisone-treated rats was different from that in irradiated, cortisone-treated rats. In the latter, cortisone treatment led to the production of liquefaction in the atelectatic lung parenchyma. The nature of the liquefaction could not be determined.

Histopathologic studies confirmed the earlier conclusion that when cortisone treatment had a beneficial effect it was more apparent if cortisone was given three days before irradiation and possibly during the first two weeks after irradiation rather than later.

Cortisone reduced the amount of fibrous and lymphoid tissue in the irradiated lung and inhibited inflammatory reaction, regardless of the time of its administration.