IMCD and BD plugs: Do they have a role in stone formation?

In contrast to the almost normal appearing (except for sites of interstitial plaque) kidneys of idiopathic calcium oxalate stone formers (ICSF), our biopsy and mapping studies that now include ten additional kidney stone forming phenotypes (see Table 1), reveals striking changes in the renal medulla noted by both endoscopic and histopathology characterized by crystalline deposits in the lumens of inner medullary collecting ducts (IMCD), and ducts of Bellini (BD) (Figure 1), with less evidence of damage in the cortex. Figure 1. Illustration showing a BD plug/overgrowth complex and other sites of crystalline deposition alone the nephron in human kidney stone formers. A crystalline deposit is noted plugging a BD and at the urinary end it is covered with an overgrowth … Continued


Three Pathways for Kidney Stone Formation          All kidney stones share similar presenting symptoms, and urine supersaturation with respect to the mineral phase of the stone is essential for stone formation. These clinical similarities have made it difficult for researchers to development treatments plans to successfully arrest stone formation for a specific stone former. However, recent studies using papillary biopsies of stone formers provide a view of the histology of renal crystal deposition which suggests that the early sequence of events leading to stone formation differs greatly depending on the type of stone and on the urine chemistry leading to supersaturation. Three general pathways for kidney stone formation (Figure 1) are seen: 1) stones fixed to the … Continued