Fig. 2

Complementary examinations (CT scan, colonoscopy, light microscopy and transmission electron microscopy) from case 1. A, B Coronal contrast-enhanced computed tomography (CT) scan at the moment of diagnosis (A) and after COVID-19 treatment (B). Panel A shows luminal narrowing and marked wall thickening involving the ascending colon, caecum, and terminal ileum. Panel B shows significant decrease in the wall thickening of the colon and terminal ileum, the lymph nodes have also decreased in size and number. C Colonoscopy at the level of the caecum reveals a mass of inflammatory appearance that predominantly affects the ileocecal valve, which is stenosed and prevents passage to the terminal ileum. D Haematoxylin and eosin staining of colonic biopsies showing abundant granulation tissue with lymphoplasmacytic inflammation and vascular proliferation (×200). E Electron micrograph of a portion of an endothelial cell showing several viral particles (red circles) lying apparently free in the cytoplasm, all separate from each other. F Close-up electron micrograph of one of the viral particles in E. The virus surface protrusions (red circle) are distinguished from confounding structures, such as ribosomes in tangential sections of the rough endoplasmic reticulum (red arrow), by the more geometric, lighter, hollow-looking appearance of the former