Unmasking a unique glomerular lesion.

Membranous-like glomerulopathy with masked IgG-κ deposits (MGMID) is a novel entity requiring antigen retrieval on formalin-fixed paraffin-embedded tissue to detect the immunoglobulin by immunofluorescence. MGMID is clinically distinct from other glomerulopathies with non-organized monoclonal IgG deposits, although the source of the kappa-restricted IgG is uncertain. Careful examination including ultrastructural analysis is essential for identifying diseases such as MGMID that may be misclassified by routine methods and ultimately require alternative techniques for accurate diagnosis.