Fig. 3

Pathological findings of lung lesions from patients with I-DiPO. (a) Low-power view of a specimen obtained from a patient with I-DiPO (Patient 19). Multiple bone foci (white stars, dendritic type, maximum size-G2) in a branching pattern or randomly located. Haematoxylin and eosin staining. (b) Multiple ossified lesions (white stars) of various sizes with or without bone marrow components. High-magnification view of the green rectangle in (a). (c) An ossified lesion with bone marrow and fat components (white star, bone marrow-G3) in the bronchial wall. High-magnification views of the area within the black rectangle in (b) and the black arrows in (c) indicate the bronchial epithelium. (d) Alveolar wall structures are observed within the ossification lesions (white stars). High-magnification view of the green rectangle in (b). The black arrow in (d) indicates the alveolar wall. (e) Multiple ossified lesions (white stars) of varying sizes. High-magnification view of the area is indicated by the black rectangle in (a). (f) CiOP lesions as dense fibrous bands (black star, CiOP-G1) observed in the vicinity of the ossifying lesions (white stars). High-magnification view of the area is indicated by the blue rectangle in (e). Scale bars: 5 mm (a), 0.5 mm (b, e), and 0.25 mm (c, d, f). CiOP cicatricial organising pneumonia, G grade, I-DiPO idiopathic diffuse pulmonary ossification, S-DiPO secondary diffuse pulmonary ossification.