Ultrastructural findings of lung injury due to Vaccine-induced Immune Thrombotic Thrombo- cytopenia (VITT) following COVID-19 vaccination: a scanning electron microscopic study

T. Congiu, D. Fanni, M. Piras, C. Gerosa, F. Cau, D. Barcellona, E. D’Aloja, R. Demontis, A. Chighine, M. Nioi, P. Coni, A. Ravarino, G. Cerrone, V. Aimola, C. Botta, A. Scano, G. Orrù, F. Coghe, P. Van Eyken, G. La Nasa, L. Saba, J.S. Suri, G. Faa, F. Marongiu

Division of Pathology, Department of Medical Sciences and Public Health, AOU of Cagliari, University of Cagliari, Cagliari, Italy. daniela.fanni@unica.it

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• Immunology

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare new syndrome occurring after the ChAdOx1 nCoV-19 vaccine immunization. Patients with VITT are characterized by a variable clinical presentation, likewise also the outcome of these patients is very variable.

Here we report the lung ultrastructural findings in the course of VITT of a 58-year-old male patient.

Alveoli were mainly dilated, irregular in shape, and occupied by a reticular network of fibrin, while interalveolar septa appeared thickened. The proliferation of small capillaries gave rise to plexiform structures and pulmonary capillary hemangiomatosis-like features. Near the alveoli occupied by a dense fibrin network, the medium-sized arteries showed a modified wall and an intraluminal thrombus.

This scenario looks quite similar to that found during COVID-19, where the lungs suffer from the attack of the antigen-antibodies complexes and the virus respectively. In both diseases, the final outcome is a severe inflammation, activation of the haemostatic system and fibrinolysis.

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