Radiologic and pathologic findings in autoimmune pneumonitis. (A) Computed tomographic scan findings were nonspecific with multifocal ground glass opacities. (B) Transbronchial biopsy showed immune peroxidase staining of lymphocytic infiltrate with reversal of CD4/8 ratio and upregulation of PD-L1 on type I pneumocytes with absent PD-1 expression. Original magnification ×100 (CD 3, 4, and 8) and ×200 (PD-L1 and PD-1).