August 15, 2017
Megalocytic Interstitial Nephritis
This biopsy shows a chronic active interstitial nephritis with numerous interstitial foamy macrophages containing abundant PAS-positive cytoplasmic granules (Fig 1-3). The findings are consistent with megalocytic interstitial nephritis. Megalocytic interstitial nephritis is an entity closely related to malakoplakia, with the absence of the characteristic Michaelis-Gutmann bodies. This entity most frequently results from a chronic, ascending, bacterial urinary tract infection, most frequently due to E. coli or other gram-negative bacteria.