Table 1.

Histopathology of cattle lung lesions following aerogenous infection with M. bovis.

Adapted from Rhyan and Saari [32]; Cassidy et al. [13, 14]; Menin et al. [33]

Histopathology of cattle lung lesions following aerogenous infection with M. bovis	Classical granuloma	Invasive necrotizing granuloma	Chronic lymphocytic « cuffing » pneumonia
Core
Central caseous necrosis of neutrophil origin	+	++ Multifocal/invasive	Inflammatory cells infiltrate perivascular or close to the bronchioles
Extra-cellular bacilli within necrotic core	++	+++
Mineralization	±	±
Mantle
Intact and degenerated neutrophils	++	+++	−
Macrophages (activated & foamy)	++	++	+
Epitheliod macrophages	++	++	+
Multinucleated giant cells (MGC)	++	+	−
Lymphocytes	+	+	+++
Cellular bacilli within macrophages and neutrophils	++	+++	ND
Periphery
Fibrous encapsulation (Collagenous connective tissue)	+++	±	−
Time of first appearance (post-infection day) [13]	28 (Circumscribing fibrosis)	14 (Large, multifocal, numerous bacilli)	7
Bacterial load (CFU)	+	+++	±
Satellite aggregations: neutrophils intact or degenerated	+	++	−