Pathology of the Macro- and Microcirculation of the Kidney

The artherosclerosis of the arteria renalis is typically limited to the proximal third of the artery. The morphological charcteristics, complications (thrombosis, emboli, aneurysm) as well as the etiology and pathogenesis are the same as in artherosclerosis of the aorta. The frequency is age dependent and it is more common in males. Stenosing artherosclerosis was seen in 5% of cases in unselected autopsies over 65 years of age. In cases with critical stenosis (over 80%) of the arteria renalis, 90% had arteriosclerosis. The changes in the ipsilateral kidney vary with age. Especially in younger patients, a pure ischemic injury will be seen. The presence of a contracted kidney with smooth surface is typical. The contraction of the kidney affects the cortex in particular; normally the weight ratio cortex to medulla is 3:2, with an ischemic contracted kidney this may reach 1:10. Histologically, closely spaced glomeruli and atrophic tubuli of the “endocrine type” (thin or barely visible basement membranes) are seen. In unselected autopsy cases an “ischemic contracted kidney” is seen in about 1%, and in patients with a history of hypertension in 5%.