Which condition is indicated by a linear appearance of glomeruli on immunofluorescence?

The condition that is indicated by a linear appearance of glomeruli on immunofluorescence is Goodpasture's syndrome. This autoimmune disorder is characterized by the presence of anti-glomerular basement membrane (GBM) antibodies, which attach to the glomerular basement membrane within the kidneys and also affect the alveolar basement membrane in the lungs.

On immunofluorescence microscopy, the glomeruli appear linear because the antibodies bind along the entire length of the glomerular capillaries. This results in a distinctive linear staining pattern, primarily due to the presence of immunoglobulin (typically IgG) and complement components along the GBM.

This finding contrasts with the different immunofluorescence patterns seen in other kidney diseases. For example, minimal change disease typically shows no significant immunofluorescence staining due to the diffuse nature of the podocyte effacement observed in this condition. Diabetic nephropathy would typically present with changes such as mesangial expansion and nodular glomerulosclerosis, along with advanced glycation end product deposits rather than a linear pattern. Focal segmental glomerulosclerosis generally displays a more patchy pattern of staining, reflecting the focal nature of the disease and the segment