Interstitial Foam Cells

This 52-year-old female underwent a renal biopsy as part of the workup for nephrotic syndrome. The biopsy is diagnostic for PLA2R-positive membranous glomerulopathy with mild glomerular and tubulointerstitial chronic injury (not shown). Interestingly, the interstitium shows frequent clusters of interstitial foam cells (see image). While foam cells are commonly associated with Alport syndrome, they may actually be seen in a wide range of renal diseases resulting in heavy proteinuria, such as focal segmental glomerulosclerosis (FSGS), membranous glomerulopathy, IgA nephropathy and in diseases with a membranoproliferative pattern of glomerular injury. While it has been shown that interstitial foam cells contain oxidized lipoproteins, their role in tubulointerstitial injury remains to be determined.