Despite strong infiltration of neutrophils under cortisone acetate treatment, growth of the fungus in bronchiolar and alveolar spaces is not prevented in the late stage of infection. (A): Multifocal to coalescing inflammatory lesion centred on bronchioles (black stars) and extending to alveoli and blood vessels. (B): Mycelium growing mainly in the bronchiolar spaces (black stars), but also extending to alveoli (arrowheads). (C): Lesions displayed a concentric organisation: in the centre, neutrophils accumulated and infiltrated bronchioles (arrowhead) and blood vessel walls (arrow). (D): Neutrophils (black star) were circled by a peripheral rim of activated macrophages (Δ). (E, F): Fungi displayed a high infiltrative potential, extending from bronchiolar spaces to alveoli. A, C, D, E: HE staining; B, F: GMS staining.