Significant polar vasculosis in a patient with a 30-year history of type 2 diabetes

Abstract

SummaryWe report the renal histology of a 66-year-old man with hypertension, cardiovascular disease, and a 30-year history of type 2 diabetes mellitus with proliferative diabetic retinopathy, diabetic neuropathy, and diabetic foot status post toe amputation. Urinary protein excretion was 1.4 g/gCr, serum creatinine level 0.86 mg/dL, estimated glomerular filtration rate 69 mL/min/1.73 m2, and HbA1c 13–15%, despite using insulin. Light microscopy showed global glomerulosclerosis in 37% of the glomeruli, but the remaining glomeruli were intact. Significant polar vasculosis was present, while arteriolar sclerosis was mild. Electron microscopy revealed a thickened glomerular basement membrane, which is compatible with the early stage of diabetic glomerulopathy. The presented case was unique because glomerular changes seen typically in diabetes were not seen in the patient, despite the long-standing history of diabetes and diabetic comorbidities, while prominent polar vasculosis was found. Polar vascular formation helps preserve the glomeruli by allowing hyperosmotic blood bypass the glomeruli; this decreases intraglomerular pressure and minimizes glomerular endothelial damage.Learning points:A 66-year-old man with a 30-year history of type 2 diabetes mellitus with poor glycemic control underwent renal biopsy, which showed scarce glomerular changes typically seen in diabetic kidney disease and instead revealed significant polar vasculosis.Past studies demonstrated that the increased small vessels around the vascular hilus in diabetic patients originated from the afferent arterioles and drained into the peritubular capillaries.Polar vascular formation may preserve glomerular function by allowing the blood flow to bypass the glomeruli and decreasing the intraglomerular pressure, which minimizes endothelial damage of the glomerular tufts.

Identification of histopathological and clinical spectrum of diabetic kidney disease based on an unsupervised hierarchical clustering analysis of elderly autopsy specimens

“…Of the 59% of patients in the non‐DKD group who had hypertension, only 3% had polar vasculosis. Oda et al speculated that polar vascular formation might aid in preserving glomerular function by decreasing the intraglomerular pressure 25 . Taken together, these findings suggest that the appearance of polar vasculosis requires not only the presence of DM, but also that of hypertension.…”

“…The patients included 25 were seen among the groups. In the hypertensive group, there were no significant differences in renal function or blood pressure between the RAS-blocker and non-RAS-blocker groups.…”

Polar vasculosis is associated with better kidney outcome in type 2 diabetes with biopsy‐proven diabetic kidney disease: A multicenter cohort study

“…Abnormal angiogenesis is involved in the pathogenesis of DKD, and the development of extra vessels, termed polar vasculosis (perihilar neovascularization), is noted as an early kidney lesion in DKD 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 . Although the exact structure of polar vasculosis is currently unknown, a study using reconstruction of three‐dimensional images suggests that these vessels are angiogenesis connecting afferent arterioles, anastomosed glomerular capillaries, efferent arterioles, and peritubular capillaries 4 .…”

“…Although the function of polar vasculosis is also unknown, it has been speculated that the formation of polar vasculosis may decrease the intraglomerular pressure 7 , 10 . We reported previously on the clinical and pathological features that affect the speed of declining kidney function in patients with biopsy‐proven diabetic nephropathy 12 .…”