Fig. 4

Pathological findings of CiOP lesions in three patients with I-DiPO. (a) Low-power view of a specimen obtained from a patient with I-DiPO (Patient 37). Multiple foci of bone (white stars, maximum size-G1 and bone marrow-G1) were observed. (b) CiOP lesions (black star, CiOP-G2) observed close to ossified lesions (white star). High-magnification view of the area in the black rectangle in (a). (c) Low-power view of a specimen from a patient with I-DiPO (Patient 28). Multiple foci of bone (white stars, maximum size-G1 and bone marrow-G2) were randomly located. (d) CiOP lesions (black stars, CiOP -G2) observed close to ossified lesions (white stars). High-magnification view of the area in the black rectangle in (c). (e) Osteoblastic cells were occasionally observed in CiOP lesions with an ossified extracellular matrix (white stars). High-magnification views of the areas in the black rectangle in (d) and the black arrows in (e) indicate osteoblastic cells. (f, g) Low- and middle-power views of a specimen from a patient with I-DiPO (Patient 14). CiOP lesions (black stars, CiOP-G2) and ossified lesions (white stars, maximum size-G3) were observed in the alveolar spaces with elastic fibre staining of serial sections (haematoxylin and eosin and Elastica van Gieson staining). (g) High-magnification view of the area in black rectangle in (f). (h) The focus of the ossified lesion (white star) is visible within the CiOP lesion (black star). High-magnification view of the area indicated by the black rectangle in (g). Scale bars, 1 mm (a, c, and f) and 0.2 mm (b, d, e, g, and h). CiOP cicatricial organising pneumonia, G grade, I-DiPO idiopathic diffuse pulmonary ossification.