American Urological Association - Renal Papillary Necrosis
Renal Papillary Necrosis
- Defined as necrosis of papillae and inner portions of renal medulla (which receives 10% of renal blood flow).
- When bilateral and diffuse, it may be associated with ARF, fever, chills, flank pain, and hematuria.
- When insidious in onset, may manifest as a concentrating defect or as progressive renal failure.
- Typically affects adults (>60 years).
- Bilateral in 70% of cases.
- May be associated with any number of disease entities, but most common is diabetes mellitus; also: analgesic abuse, sickle cell disease.
- Pathogenesis is ischemic, related to marginal blood supply of medulla (which explains prevalence in patients with underlying vascular disorders such as diabetics); also vasoconstriction due to prostaglandin inhibition by NSAID.
- Gross: necrosis of renal papillae/medullary portion (image A).
- Coagulative necrosis rimmed by acute inflammation (image B).
- Minimal inflammation at necrotic area.
- Necrosis usually does not involve the entire medulla.
- From a vascular standpoint, the papillary tip is the most vulnerable, so it is the first to go.
- Because the necrosis is induced by ischemia, it typically has a coagulative appearance (ghost cells).
- Microcalcifications may be present.
- Renal changes of cause: diabetes nephropathy (diffuse nodular mesangial sclerosis), analgesic nephropathy (interstitial fibrosis, tubular atrophy, capillary sclerosis), and sickle cells (sickling in blood vessels) can be seen.
- Prognosis depends on the causative factor and extent of damage and varies (diabetes worst).