In a specimen of kidney, fibrinoid necrosis is seen and onion- peel appearance is also present. Most probable pathology is: (AIIMS Nov 2012)
Histological alterations characterizing blood vessels in malignant hypertension
• Fibrinoid necrosis of arterioles: This appears as an eosinophilic granular change in the blood vessel wall, which stains positively for fibrin by histochemical or immunofluorescence techniques.
• In the interlobular arteries and arterioles, there is intimal thickening caused by a proliferation of elongated and concentrically arranged smooth muscle cells with deposition of collagen. This alteration has been referred to skinning because of its concentric appearance. The lesion also called hyperplastic arteriolitis, correlates well with renal failure in malignant hypertension.
• Malignant nephrosclerosis is the form of renal disease associated with the malignant or accelerated phase of hypertension. pinpoint petechial hemorrhages may appear on the cortical surface from rupture of arterioles or glomerular capillaries, giving the kidney a peculiar "flea-bitten" appearance.
• Hyaline arteriolosclerosis is narrowing of the lumens of arterioles and small arteries, caused by thickening and hyalinization of the walls. It is seen with Benign nephrosclerosis. Nephrosclerosis is associated with increasing age, more frequent in blacks than whites, and may be seen in the absence of hypertension. Hypertension and diabetes mellitus however, increase the incidence and severity of the lesions.