Figure 6c.

PD-1 inhibitor pneumonitis: Hypersensitivity pneumonitis pattern in a 68-year-old man with metastatic renal cell carcinoma who was treated with nivolumab and presented with a new cough at 6 months of therapy. (a) Axial chest CT image shows new multifocal GGOs in a centrilobular distribution throughout both lungs and mosaic attenuation, findings that represent pneumonitis with a hypersensitivity pneumonitis pattern. Nivolumab therapy was withheld, and the patient underwent corticosteroid therapy. (b) Axial follow-up CT image obtained after 1 month of corticosteroid therapy shows marked improvement of pneumonitis and resolution of GGOs. Nivolumab continued to be withheld, and corticosteroid therapy was tapered. At 1.5 months after completing the corticosteroid taper, without restarting nivolumab or any other systemic therapy, the patient experienced a worsening cough. (c) Axial chest CT image shows development of diffuse GGOs with areas of air trapping, findings indicative of pneumonitis with a hypersensitivy pneumonitis pattern. The radiographic pattern of this second episode is similar to that noted in the initial episode and represents pneumonitis flare.