Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology
Fibrinoid necrosis is a special type of necrosis that can be seen in blood vessel walls. It is associated with immune-complex vasculitis and hypertension. Immune complexes, complement and plasma proteins deposit in damaged vessel walls, giving the tissue a smudgy, bright pink appearance on histological examination.
This pattern of necrosis is prominent when complexes of antigens and antibodies are deposited in the walls of arteries. Deposits of these "immune complexes," together with fibrin that has leaked out of vessles, results in a bright pink and amorphous appearance in H&E stains, called "fibrinoid" (fibrin-like).
Fibrinoid necrosis is a histopathological hallmark of malignant hypertension (blood pressure greater than 200/130 mmHg).
Malignant hypertension and polyarteritis nodosa are common causes.