PMC8720767_01
Photographs from gross post-mortem examination of an adult castrated male Vietnamese pot-bellied pig with acute dyspnea and lethargy. (A) The pleural cavity contains a moderate amount of dark red serosanguinous effusion with abundant fibrin along the pleura of the left lung lobes, ventral right lung lobes, and adjacent pericardial sac. The left caudal lung lobe (denoted by white arrowheads) is markedly expanded and displaced to the right of the midline. (B) On cut surface, the left lung lobe is markedly expanded by multifocal granulomas with dry yellow to tan caseonecrotic centers (*) surrounded by firm, smooth, pale tan, fibrous tissue that blends into adjacent pulmonary parenchyma. The interlobular septa of the adjacent lung are moderately expanded with edema (arrowheads).
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F1
Approximately 90% of the left cranial and caudal lung lobes were replaced by two, large, firm, tan masses measuring 12 x 11 x 6 cm and 14 x 13 x 12 cm (Figure 1A). On cut surface, the pulmonary masses had a dry, yellow to tan, malodorous caseonecrotic center surrounded by abundant firm, smooth, pale tan, fibrous tissue that blended into the adjacent pulmonary parenchyma (Figure 1B). The adjacent interlobular septa were moderately expanded by edema (Figure 1B).
Photomicrographs of sections of lung obtained from the pig in Figure 1. (A,B) The pulmonary parenchyma is largely effaced by multifocal to coalescing granulomas centered around non-staining hyphae highlighted by bright eosinophilic "sleeves" of Splendore-Hoeppli material (arrows) with degranulating and intact eosinophils (highlighted in the inset). Surrounding this is a layer of multinucleated giant cells and epithelioid macrophages (arrowhead), which are bordered by a thick band of lymphocytes and plasma cells (*). Coalescing between these granulomas is abundant dense fibrous stroma (+). H&E stain; bar = 500 mum (A), 50 mum (B), 10 mum (B inset). (C) Higher magnification view showing 7-14 mum diameter, non-staining hyphae (arrow) with occasional non-dichotomous branching highlighted by brightly eosinophilic sleeves. H&E stain; bar = 20 mum. The inset illustrates positive staining of hyphae with GMS. Bar = 20 mum. (D) Hyphae (arrows) also stain weakly positive with PAS, which illustrates the infrequent septation and non-parallel walls of these hyphae. Bar = 20 mum.
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F2
Lymphocytes and plasma cells were peripherally placed and merged with a dense fibrous capsule (Figures 2A,B). These stains highlighted additional features of the fungi, including non-parallel walls, infrequent septation, and occasional non-dichotomous branching (Figures 2C,D).