Case report: intraglomerular metastasis with neoplastic cell interposition.

A case is described of an 88-year-old man with lung cancer, nephrotic syndrome, and renal dysfunction who died suddenly of an acute myocardial infarction and whose autopsy revealed many adenocarcinoma cells stacked within glomerular capillary lumina of his kidney, entering into basement membrane zones (ie, neoplastic cell interposition). In addition, glomeruli showed a lobular transformation, doubling of glomerular basement membrane, and electron dense deposits along the glomerular basement membrane. These changes were similar to those of membraneoproliferative glomerulonephritis. The association of intraglomerular metastasis and membranoproliferative glomerulonephritis-like lesions led the authors to speculate that the latter glomerular change might have provided an attractive opportunity for circulating tumor cells to be trapped and grow within the glomerular lumina. This mode of metastasis has not been well-recognized. The authors describe the experience, review the literature, and discuss its possible pathogenesis.