Renal Medullary Necrosis

THE PATHOGENESIS of renal medullary (or papillary) necrosis is still quite obscure. The lesion has all the earmarks of an ischemic infarct, in the absence of obstruction of a major blood vessel. Furthermore, the necrosis never involves the cortex. An apparent counterpole to this lesion is symmetrical cortical necrosis, a pathologic entity for itself, which is commonly found in association with pregnancy and with acute systemic diseases of infectious or "hypersensitivity" nature1; experimentally, it is a consistent and major characteristic of the generalized Shwartzman phenomenon.2Papillary necrosis, which may be unilateral or bilateral, usually represents a serious complication of pyelonephritis and is therefore most frequently encountered in patients suffering from diabetes or urinary obstruction, or both.3Clear evidence of either of these two conditions was lacking in only 10% of the 180 cases published up to January 1953.4 Knutsen and his associates4aconcluded from their study of 16 cases that,