Thickening of the renal arteriolar wall with hypertensive emergency ("malignant" hypertension) when systolic pressure is ≥180 and/or diastolic pressure ≥120 mmHg along with signs of acute or ongoing end-organ damage is associated with a hyperplastic arteriolosclerosis (hyperplastic arteriolitis). This arteriole has an "onion skin" appearance to the media. The thickening has left a tiny lumen.