COVID-19 vasculitis and novel vasculitis mimics

Area of Science:

• Pulmonary and Systemic Pathology
• Infectious Disease Complications
• Vascular Medicine

Background:

• COVID-19 is linked to cutaneous vasculitis and Kawasaki-like disease, typically with good prognosis and minimal lung impact.
• Severe COVID-19 pneumonia can manifest with vasculitis-like lesions and systemic thromboemboli, including cryptogenic strokes.
• Proposed mechanisms include immune dysregulation, antiphospholipid syndrome, complement activation, and direct endothelial infection.

Purpose of the Study:

• To highlight a novel thrombosis in the pulmonary venous territory in severe COVID-19 pneumonia.
• To propose this thrombosis as a nidus for systemic microembolism.
• To suggest this mechanism explains various COVID-19-associated systemic complications mimicking vasculitis.

Main Methods:

• Review of imaging and post-mortem findings in COVID-19 patients.
• Analysis of pathological reports detailing pulmonary and peripheral organ thrombosis.
• Correlation of findings with clinical manifestations of systemic complications.

Main Results:

• Identification of novel thrombosis in the pulmonary venous territory distal to the alveolar capillary bed.
• Evidence suggests this thrombosis acts as a nidus for systemic microembolism.
• Pathological reports show extensive pulmonary venular thrombosis and peripheral organ thrombosis with pauci-immune infiltrates.

Conclusions:

• Severe COVID-19 pneumonia is associated with extensive pulmonary intravascular coagulopathy.
• This coagulopathy may explain numerous systemic complications, including cryptogenic strokes, acute kidney injury, and skin vasculitis mimics.
• The findings suggest a novel mechanism for COVID-19-related organ damage beyond direct viral infection.