Early Pathologic Findings of Bronchiolitis Obliterans after Allogeneic Hematopoietic Stem Cell Transplantation: A Proposal from a Case

Figure 2

Pathological findings of the TBLB and autopsy. In the TBLB specimens, Victoria blue staining shows the narrowing of bronchioles (a-i) with infiltration of lymphocytes in bronchial walls. There are no fibrotic lesions (a-ii). In the lung tissue at autopsy, there is extensive obliteration or disappearance of bronchioles due to prominent smooth muscle hypertrophy and submucosal collagen deposition (b). Elastica van Gieson staining shows preexisting elastic fibers of the bronchiolar wall with complete fibrous obliteration, which suggests that there was the end-stage obstruction of bronchiole (arrow heads) with fibrotic tissues, surrounded by elastic fibers (black). Residual bronchial arteriole (arrow) is also observed (c). Infiltration of lymphocytes and macrophages into bronchial wall (d-ii) was occasionally observed in residual bronchioles (d-i) by Masson’s Trichrome staining (blue; collagen layer in bronchial wall).