What Open-Lung Biopsy Teaches Us about ARDS in COVID-19 Patients: Mechanisms, Pathology, and Therapeutic Implications

Table 3

Histological features of lung biopsy patients.

	Case 1	Case 2	Case 3
Alveoli	Variable size	Variable size	Enlarged +++
	Collapsed +++	Collapsed +++	Collapsed +
		Enlarged +
Interalveolus wall	Thickened +++	Thickened +++	Thickened ++
			Dystrophic +
Type II pneumocyte	(i) Hyperplasic +++; (ii) Atypical; (iii) Multinucleated; (iv) Enlarged	(i) Hyperplasic +++; (ii) Atypical; (iii) Multinucleated; (iv) Enlarged	(i) Discontinuous; (ii) Hyperplasic ++
Alveolar cavity:
(i) hyaline membrane; (ii) exudate; (iii) alveolar hemorrhage	+++	+++	++
	+++	+++	++
	+	0	+
Interstitial tissue: (i) inflammatory infiltrate	(i) Diffused; (ii) Minimal; (iii) Lymphocyte +++; (iv) Eosinophilic polynuclear ++	(i) Diffused; (ii) Minimal; (iii) Lymphocyte +++; (iv) Eosinophilic polynuclear ++; (v) Neutrophil polynuclear ++; (vi) Multinucleated giant cells +	(i) Diffused; (ii) Minimal; (iii) Lymphocyte +; (iv) Plasmocyte ++; (v) Macrophage +; (vi) Fibroblast ++
Microthrombi	+ + +	+ + +	+ +
Vascular congestion	+ + +	+ + +	+ + +
Consolidation	45%	55%	60%
Alveolar fibrosis (Masson trichrome staining)	Negative	Negative	Negative
Coinfection (periodic acid-Schiff staining)	Negative	Negative	Negative

The intensity was appreciated independently by two investigators and estimated. “+”: focal; “++”: plurifocal; “+++”: diffuse.