ABSTRACT
Human morbidity and mortality associated with the infection SARS-CoV-2 is mainly due to pneumonia.
The histological pattern of lungs is characterized by diffuse alveolar damage (DAD) and hyaline membranes. Vascular changes, including endothelial disfunction in the alveolar septal capillaries followed by thrombosis and disseminated intravascular coagulation, are frequently associated.  Recently, further microvascular changes leading to new blood vessel growth through intussusceptive angiogenesis and distortion of microvascular architecture have been reported in lungs from patients died because of COVID-19. Here we report a case of COVID-19 in a 63-year-old patient affected by progressive respiratory failure. At histology, DAD was associated with distinctive vascular changes, including alveolar capillary microthrombi and thrombosis of arterial vessels. Moreover, a marked proliferation of small capillaries extending from the alveolar septa and compressing the adjacent alveoli was observed, allowing the diagnosis of pulmonary capillary hemangiomatosis (PCH). This report of PCH in a patient affected by COVID-19 reinforces the hypothesis of the major role played by endothelial dysfunction, capillary thrombosis and neoangiogenesis in SARS-CoV-2 infection and suggests that new blood vessel growth may evolve toward PCH, ending to the disruption of lung architecture.

IMPACT STATEMENT
Endothelial dysfunction, capillary thrombosis and neoangiogenesis with new blood vessel growth induced by SARS-CoV-2 may evolve toward pulmonary capillary hemangiomatosis and lung architecture disruption.