Figure 7a.

PD-1 inhibitor pneumonitis flare in a 72-year-old man with stage IV squamous NSCLC who was treated with nivolumab and presented with progressive dyspnea with cough and wheezing but no fever. (a) Axial chest CT image at 15 weeks of therapy demonstrates multifocal areas of GGOs, reticular opacities, and consolidation (arrows) involving all lobes, as well as centrilobular nodularity and traction bronchiectasis in a predominantly peripheral distribution. The overall features demonstrate a COP pattern. The patient was treated with prednisone for pneumonitis. (b) Axial follow-up CT image after 4 weeks of prednisone therapy shows a significant decrease in the findings, with residual GGOs. Note the “reversed halo” sign manifesting as a central GGO surrounded by a crecent-shaped dense airspace consolidation (arrow), a finding that has been reported as a radiologic manifestation of COP. (c) Axial CT image obtained 4 weeks after the completion of prednisone therapy shows the development of a bilateral dense consolidation with GGOs and reticular opacities (arrows) in peripheral and multifocal distributions, again demonstrating a COP pattern as noted during the first episode of PD-1 inhibitor pneumonitis. Given the similarity of the radiologic and clinical manifestations to those of the first episode, the patient restarted prednisone for treatment of pneumonitis flare. Follow-up chest CT images obtained 2 weeks after starting the second course of prednisone therapy (not shown) demonstrated a decrease in the findings, indicative of improving pneumonitis in response to corticosteroid therapy. (Figure 7 reprinted from reference 21.)