Calcium Oxalate Crystals Are Present in Acquired Cystic Kidney Disease in End-Stage Renal Disease (ACKD-ESRD) but Not in Autosomal Dominant Polycystic Kidney Disease (ADPKD) – Does This Signify a Role in Cancer Development?
Maria M Picken, Vikas Mehta. Loyola University Medical Center, Maywood, IL
Background: In both ACKD-ESRD and ADPKD, numerous cysts develop and renal failure ensues. When compared with the general population, in ACKD-ESRD there is a 100-fold increase in renal cancer risk, while in ADPKD the risk is much lower. The pathogenesis of malignancy in ACKD-ESRD is not well understood, but certain cancers that are unique to ACKD-ESRD are associated with calcium oxalate crystals. Hence, their presence has been implicated in the pathogenesis of these cancers. The aim of this study was to asses the prevalence of calcium oxalate crystals in nephrectomies from patients with ACKD-ESRD versus ADPKD.
Design: We reviewed, retrospectively, all the nephrectomies performed in our department between 1985 and 2010 in patients with ADPKD and ACKD-ESRD. We compared the pathology of tumors in ADPKD and in ACKD-ESRD and evaluated the specimens for the presence or absence of calcium deposits. In H&E slides, calcium oxalate crystals were identified under polarized light, while calcium apatite crystals showed only a bluish color and no polarization.
Results: 42 patients (19 M/23F) with ADPKD underwent 73 nephrectomies; in 7/42, both kidneys were removed but not simultaneously. Mean age was 50.3 yrs (range, 31-71yrs). 4 nephrectomies showed RCC (5.4%): 3/4 clear cell RCC and 1/4 papillary RCC; all in male patients. There was also fibrosis and hemorrhages in the cyst wall. Blue crystals of calcium apatite were seen in 33/42 ADPKD nephrectomies, while none showed calcium oxalate crystals. Eighty patients with ESRD (44 M/36F) underwent 97 nephrectomies. RCC was seen in 32 patients (25M/7F): clear cell RCC in 16/32, papillary RCC in 7/32, acquired cystic disease associated RCC in 7/32, sarcomatoid and chromophobe RCC in one each. Calcium oxalate crystals were identified in 42 ACKD-ESRD; 2 tumors with abundant calcium oxalate crystals were classified as calcium-oxalate associated RCC. Only 4 ACKD-ESRD kidneys, all without malignancy, showed blue crystals of calcium apatite.