V.2.2. Cytology & Pathology
From a pathophysiological viewpoint, direct evidence of an eosinophilic
type 2 inflammation associated with and attributed to a fungus is
compelling evidence for ongoing fungal allergic disease. Direct
microscopic examination of naso-sinusal, bronchial, or sputum samples
may be performed in search of eosinophilic inflammation with fungal
non-invasive colonization of thick mucus plugs (89). Eosinophils,
eosinophilic inflammation markers such as Charcot-Leyden crystals, and
fungal hyphae were recently proposed as pathognomonic for ABPA/ABPM
(88).