Staining of pulmonary parenchyma. H&E: (A) Atypical tubular-gland structures of decidual lesions were detected in the alveolar space (thin arrow). Structure of alveolar wall (thick arrow); 100×. (B) The alveolar spaces were filled with many red blood cells and phagocytic cells with hemosiderin (thick arrow). The alveolar walls were infiltrated by plasma cells (triangular arrow) and lymphocytes (thin arrow); 200×. Immunohistochemical staining: (C) Phagocytic cells in the alveolar space, CD68+ (heavy arrow). Plasma cells and lymphocytes in the alveolar walls, CD68– (thin arrow), H&E 200×. (D) Gland epithelium in an alveolus, CK7+ (thick arrow). Infiltrating plasma cells and lymphocytes in the alveolar wall, CK7– (thin arrow), H&E 200×. H&E: hematoxylin and eosin (correct).