Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and coronavirus disease 19 (COVID-19) - anatomic pathology perspective on current knowledge

Abstract

Background: The world is currently witnessing a major devastating pandemic of Coronavirus disease-2019 (COVID-19). This disease is caused by a novel coronavirus named Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). It primarily affects the respiratory tract and particularly the lungs. The virus enters the cell by attaching its spike-like surface projections to the angiotensin-converting enzyme-2 (ACE-2) expressed in various tissues. Though the majority of symptomatic patients have mild flu-like symptoms, a significant minority develop severe lung injury with acute respiratory distress syndrome (ARDS), leading to considerable morbidity and mortality. Elderly patients with previous cardiovascular comorbidities are particularly susceptible to severe clinical manifestations. BODY: Currently, our limited knowledge of the pathologic findings is based on post-mortem biopsies, a few limited autopsies, and very few complete autopsies. From these reports, we know that the virus can be found in various organs but the most striking tissue damage involves the lungs resulting almost always in diffuse alveolar damage with interstitial edema, capillary congestion, and occasional interstitial lymphocytosis, causing hypoxia, multiorgan failure, and death. A few pathology studies have also reported intravascular microthrombi and pulmonary thrombembolism. Although the clinical presentation of this disease is fairly well characterized, knowledge of the pathologic aspects remains comparatively limited.

Conclusion: In this review, we discuss clinical, pathologic, and genomic features of COVID-19, review current hypotheses regarding the pathogenesis, and briefly discuss the clinical characteristics. We also compare the salient features of COVID-19 with other coronavirus-related illnesses that have posed significant public health issues in the past, including SARS and the Middle East Respiratory Syndrome (MERS).

Keywords: Autopsy; COVID-19; Pathogenesis; Pathology.

Fig. 1

Electron micrograph of the intracellular virus-like particles of a COVID-19 victim (“Courtesy of Martin Herzig for technical preparation and performing the microphotography”)

Fig. 2

Pathogenesis of COVID-19

Fig. 3

a and b Imaging in COVID-19 showing widespread bilateral interstitial and airspace opacities (3B: “Courtesy of Dr. Maurice Henkel”)

Fig. 4

Gross Images of a COVID-19 lung with a interstitial edema and congestion; b pulmonary embolism in COVID-19

Fig. 5

Diffuse alveolar damage in COVID-19. Note prominent hyaline membranes. (Hematoxylin & eosin, original magnification × 200). There is no evidence of “diffuse microthrombi”

Fig. 6

Interstitial inflammation in COVID-19. The inflammatory cells are predominantly lymphocytes (Hematoxylin & eosin, original magnification × 200)

Fig. 7

COVID-19 lung with microthombi casting the capillaries of the alveoli (Fibrin stain, original magnification × 200)

Fig. 8

Airway inflammation in COVID-19: a Chronic inflammation composed mainly of lymphocytes, involving the bronchial mucosa (Hematoxylin & eosin, original magnification × 200). Note that blood vessels are free of thrombi; b CD3 demonstrates T-lymphocytes