Ultrastructural characteristics and differential diagnosis of immunotactoid glomerulonephritis

Objective To explore the ultrastructural characteristics and differential diagnosis of immunotactoid glomerulonephritis, one kind of rare glomerular diseases. Methods Renal biopsy samples sent to the Laboratory of Electron Microscopy of Peking University First Hospital from 2019 to 2024 were retrospectively observed and analyzed. They were routinely treated for transmission electron microscopy sample preparation, including fixation, dehydration, permeation, embedding, ultra-thin sectioning, and staining. Results and Discussion Among the 36 481 samples, 13 cases were diagnosed with immunotactoid glomerulonephritis, characterized by long and thick microtubules mainly distributed in the subendothelial and mesangial areas, often accompanied by significant infiltration of neutrophils. The main differential diagnosis includes other diseases accompanied by fibrous or tubular structure formation, including fibrillary glomerulonephritis, cryoglobulinemic glomerulonephritis, lupus nephritis, cryofibrinogen associated glomerulonephritis, type Ⅲ collagen glomerulopathy, nail-patella syndrome, etc. Conclusions Transmission electron microscopy plays a crucial role in the diagnosis and differential diagnosis of immunotactoid glomerulonephritis.