Collapsing glomerulopathy superimposed on diabetic nephropathy: insights into etiology of an under-recognized, severe pattern of glomerular injury.

BACKGROUND: Collapsing glomerulopathy (CG) represents severe podocyte injury with massive proteinuria, rapid progression and relative resistance to therapy. It is associated with multiple etiologies, including obliterative arteriopathy in transplants. However, its association with diabetic nephropathy (DN) has not been reported. METHODS: Renal biopsies performed in diabetic patients for either increasing proteinuria or deteriorating renal function, or both, were retrospectively reviewed. The clinicopathologic features and immunohistochemical staining of podocytes were analyzed. RESULTS: Of 534 patients with DN, 26 human immunodeficiency virus (HIV)-negative patients were found to have CG superimposed on DN (5% DN cases). At the time of biopsy, their mean serum creatinine was 3.8 mg/dL and proteinuria was 9.8 g/24 h. Renal biopsy showed CG in 2-30% (mean 16% of glomeruli), with segmental (2%) and global (33%) glomerulosclerosis. DN classification was Class IV-12, III-8, IIb-4 and IIa-2. Vascular sclerosis was moderate (44%) and severe (56%). Extensive arteriolar hyalinosis with >50% luminal stenosis was seen in 85% of cases. Markers of podocyte differentiation were lost, consistent with other types of CG. Cytokeratin was focally positive in 70% and VEGF overexpressed in 43%. Follow-up on 17 patients: 13 developed end-stage renal disease (ESRD) in 7 months from the time of biopsy. The development to ESRD in these patients was more rapid than diabetic controls without CG (P=0.005). The remaining four, 5-24 months follow-up, had an increase in creatinine with stable proteinuria. CONCLUSIONS: CG contributes to an increased level or new onset of proteinuria in DN which may be intractable. CG in DN with advanced vascular hyalinosis is presumably due to ischemic podocyte injury and is of prognostic significance.

Adenomatous Colon Polyps in Diabetes: Increased Prevalence in Patients with Chronic Kidney Disease and Its Association with Parathyroid Hormone.

Previous studies have shown a higher prevalence of malignancy in patients with diabetes mellitus (DM) and chronic kidney disease (CKD). The purpose of this study was to investigate the prevalence of adenomatous colon polyps (ACP) as they occur in subjects with DM and coexisting CKD. This is a retrospective cohort study of patients with DM (n=565) who had undergone colonoscopy between 2000-2010. The cohort was further bifurcated into those with CKD (n=296) and those with normal renal function (n=269). Presence or absence of ACP was measured in both groups. Concentrations of serum parathyroid hormone (PTH), Calcium (Ca), and phosphorous (P) were recorded for the CKD group. The levels of these variables in patients with ACP (n=171) were compared with the levels from those without ACP (n=175). Nonparametric statistical methods were applied with statistical significance suggested by p<0.05 (two-sided). The presence of CKD in this cohort demonstrated a significant association with ACP (OR: 2.96; 95% CI: 2.02 to 4.34; p<0.0001). We did not detect a statistically significant difference in P or Ca between the groups. There was, however, a statistically significant difference in PTH; for the group with ACP, PTH: 387.7±351.3 ng/L vs. 172.2±196.7 ng/L; p<0.0001. This data suggests that CKD is associated with ACP in subjects with DM and those with ACP exhibit higher PTH levels when compared to those without ACP.

Clinicopathological spectrum of kidney diseases in cancer patients treated with vascular endothelial growth factor inhibitors: a report of 5 cases and review of literature.

Recently, cancer therapies have been supplemented by vascular endothelial growth factor (VEGF) inhibitors as anti-angiogenic agents. However, kidney-related adverse reactions associated with these agents clinically manifest as hypertension and proteinuria, the most severe form being thrombotic microangiopathy (TMA). We present the spectrum of pathological features in VEGF inhibitor-associated kidney disease. Clinicopathological findings of kidney disease were retrospectively studied in 5 cancer patients treated with anti-VEGF agents. Although 4 cases received bevacizumab (anti-VEGF-A), one was given sorafenib (small molecule tyrosine kinase inhibitor affecting VEGF-R2). All patients presented with acute kidney injury, hypertension, and/or proteinuria. All kidney biopsies showed recent and chronic endothelial injury of varying severity and vascular sclerosis, including 2 with typical active features of TMA. Furthermore, acute tubular injury with focal necrosis was seen in all cases. While administration of VEGF inhibitor was discontinued in 4 cases, it was resumed for 5 more doses, following steroid therapy in 1 case. Cessation of VEGF inhibitor therapy was successful in reversing anemia and led to improvement of hypertension and proteinuria in 4 of the 5 cases. One case with TMA progressed to end-stage renal disease. A range of renal pathologic lesions secondary to endothelial injury are noted often accompanied by acute tubular damage following anti-VEGF therapy, the most severe being TMA. While most of the clinical manifestations are reversible with discontinuation of therapy, the role of other nephrotoxic chemotherapeutic agents in enhancing renal injury including severe TMA and other host factors with possible poor outcome should be considered.