Radiographic and histology findings

(A) CT abdomen with oedema of the small bowel wall. (B) Mucosal necrosis with microvascular thrombi and fibrin extravasation in lamina propria, consistent with thrombogenic vasculopathy (haematoxylin and eosin). (C) Occlusive luminal thrombi and mural fibrin (haematoxylin and eosin). (D–I) In situ deposition of components of complement activation, namely C3d, C4d, C5b-9 and MASP2, the latter a protein formed as a sequelae of the mannose-lectin binding activation were conducted on 4-μm sections procured from formalin-fixed paraffin-embedded tissue. Immunohistochemical assessment of SARS-CoV-2-associated envelope and spike glycoprotein was also conducted, as previously described [4]. (D) MASP2 staining, (E) C4d staining in thrombosed and (F) non-thrombosed capillaries and venules (diaminobenzidine), and (G) C5b-9 staining of (H) SARS-CoV-2 membrane and (I) spike glycoprotein throughout the microvasculature ( diaminobenzidine). MASP2: mannose-binding lectin serine protease 2 SARS-CoV-2: severe acute respiratory distress syndrome coronavirus 2. Scale bar = 100 μm.