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Table 4 Criteria used for the classification of lungs based on histologic examination


Histological lesion category Description
Abscess Thick fibrous capsule (or part thereof) surrounding viable +/− degenerate neutrophils +/− central liquefactive necrosis
Bronchopneumonia Alveolar and bronchial/bronchiolar lumina filled with admixed neutrophils, macrophages and lymphocytes, +/− type 2 pneumocyte hyperplasia, bronchiolitis obliterans, oedema, bacterial colonies, regions of fibrosis
Interstitial thickening Extensive-diffuse, mild-marked thickening of the alveolar septa due to smooth muscle hypertrophy +/− fibroblasts.
Histologically Suspect OPA (HSO) Single-multifocal, well-demarcated-infiltrative tumours with papillary/lepidic/acinar growth patterns consisting of cuboidal-columnar cells supported by a fine fibrous stroma and surrounded by macrophage infiltration.
Parasitic infestation One or more of the following: nematode eggs/larvae, eosinophilic granulomas, eosinophil-rich interstitial and intra-alveolar infiltrates.
Other Pathological changes not falling into any of the other categories described.
Normal No pathological changes