Arteriolosclerosis
Arteriolosclerosis is a form of cardiovascular disease involving hardening and loss of elasticity of arterioles or small arteries and is most often associated with hypertension and diabetes mellitus. Types include hyaline arteriolosclerosis and hyperplastic arteriolosclerosis, both involved with vessel wall thickening and luminal narrowing that may cause downstream ischemic injury. The following two terms whilst similar, are distinct in both spelling and meaning and may easily be confused with arteriolosclerosis. Hyaline arteriolosclerosis. Also arterial hyalinosis and arteriolar hyalinosis refers to thickening of the walls of arterioles by the deposits that appear as homogeneous pink hyaline material in routine staining . It is a type of arteriolosclerosis, which refers to thickening of the arteriolar wall and is part of the ageing process. It is associated with aging, hypertension, diabetes mellitus and may be seen in response to certain drugs (calcineurin inhibitors). It is often seen in the context of kidney pathology. In hypertension only the afferent arteriole is affected, while in diabetes mellitus, both the afferent and efferent arteriole are affected. Lesions reflect leakage of plasma components across vascular endothelium and excessive extracellular matrix production by smooth muscle cells, usually secondary to hypertension. Hyaline arteriolosclerosis is a major morphologic characteristic of  benign nephrosclerosis, in which the arteriolar narrowing causes diffuse impairment of renal blood supply, with loss of nephrons. The narrowing of the lumen can decrease renal blood flow and hence glomerular filtration rate leading to increased renin secretion and a perpetuating cycle with increasing blood pressure and decreasing kidney function. Hyperplastic arteriolosclerosis. This is a type of arteriolosclerosis involving a narrowed lumen. The term "onion-skin" is sometimes used to describe this form of blood vessel with thickened concentric smooth muscle cell layer and thickened, duplicated basement membrane. In malignant hypertension these hyperplastic changes are often accompanied by fibrinoid necrosis  of the arterial intima and media. These changes are most prominent in the kidney and can lead to ischemia and acute kidney failure. It can be caused by malignant hypertension.