case_images: PMC10601932_01
case_images: a Glomeruli exhibiting a lobular appearance due to endocapillary and mesangial proliferation (white arrow) with segmental pseudothrombi (black arrow) (hematoxylin-eosin stain, x20). b Pseudothrombi are positively stained with periodic acid-Schiff (PAS stain, x20). c Fuchsinophilic capillary wall pseudothrombi (Masson trichrome stain, x20). d Double contours of the glomerular basement membranes (red circle) (Jones silver stain, x 20).
case_images: gdz-2023-0003-0001-531737_F01.jpg
case_images: PMC10601932_01_gdz-2023-0003-0001-531737_F01.jpg
case_images: F1
case_images: The rest showed mesangial expansion, associated with endocapillary and mesangial proliferation with the presence of double contours in the methenamine silver staining (Fig. 1a-d). Focally, the glomerular capillary lumens were occupied by large intraluminal PAS-positive material without platelet aggregates (CD61-negative), compatible with pseudothrombi (Fig. 1a-c).
case_images: a, b Immunofluorescence staining reveals IgA and C3 positivity in pseudothrombi (original magnification x4,000). c EM shows doubles contours of the glomerular basement membranes (black arrow) and subendothelial electron-dense deposits (white arrow). d Intravascular immunotactoid deposits which occlude the vascular lumens (original magnification x30,000). The image on the right displays a higher magnification view, revealing disorganized arrangement of tangle-like or tubular structures, with mean thickness of 29,94 nm (original magnification x40,000).
case_images: gdz-2023-0003-0001-531737_F02.jpg
case_images: PMC10601932_01_gdz-2023-0003-0001-531737_F02.jpg
case_images: F2
case_images: IgG (1+), C3 (3+), C4d (3+), lambda (3+), and kappa (3+) light chains without restriction, localized segmentally to the capillary walls with more intense staining in pseudothrombi (Fig. 2a, b). IF-F was negative for IgM, C1q, and fibrinogen. IgG subtyping was not performed. EM showed amorphous subendothelial and mesangial deposits and organized electrodense deposits within capillary loops (pseudothrombi) with microtubular substructure measuring 20-40 nm in thickness (Fig. 2c, d).