Plugging of airways with mucus

B. After suction the material was seen to extend distally - obstructing the right basal stem bronchus

Initially it was incorrectly diagnosed as a bronchial carcinoma.
The material was allergic mucin with mucus and cellular debris arranged in a layered pattern. Cellular debris was almost entirely eosinophils with scattered Charcot-Leyden crystals. A Grocott stain showed multiple branching fungal hyphae, consistent with Aspergillus spp. Subsequently her total IgE rose to  750 KIU/L and Aspergillus specific RAST to 14.9 KUa/L.