Renal papillary necrosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Nasrin Nikravangolsefid, MD-MPH [2]
Overview
Renal papillary necrosis is a form of nephropathy involving the ischemic necrosis of the renal papilla, which is supplied by the vasa recta. Renal papillary necrosis is a significant kidney disorder, which is associated with chronic conditions such as diabetes, sickle cell disease, urinary tract obstruction, urinary tract infection and long term use of analgesics containing phenacetin.
Historical Perspective
Renal papillary necrosis was first introduced by Friedrich in 1877, following urinary obstruction. Then, other associated factors such as diabetes, sickle cell disease and analgesics have been found.
Pathophysiology
It is thought that Renal papillary necrosis is the result of damage to interstitial medullary and papillary cells due to direct effect of diseases such as diabetes, sickle cell disease, urinary tract obstruction, renal vein thrombosis, upper urinary tract infection, tuberculosis, vasculitis, renal transplant rejection and long term analgesics use such as acetaminophen and NSAIDs. Decreased prostaglandin synthesis and subsequent reduced renal blood flow is an important mechanism for developing renal papillary necrosis. Accumulation of sickle-shaped RBCs in patients with sickle cell disease can lead to intravascular obstruction, blood stasis and thrombosis that results in ischemic necrosis of renal papillary and medullary cells.
Causes
Renal papillary necrosis is associated with damaging the renal medullary and papillary cells due to many diseases such as diabetes, sickle cell disease, urinary tract obstruction, renal vein thrombosis, pyelonephritis, tuberculosis, vasculitis, cirrhosis, renal transplant rejection and long term analgesics and alcohol abuse. In infants, it is associated with asphyxia, dehydration, and sepsis.
Classification
Renal papillary necrosis may be classified according to the severity of renal parenchymal lesions into two subtypes: Medullary and Papillary.
Differential Diagnosis
Renal papillary necrosis should be differentiated from other conditions presenting with acute flank or upper abdominal pain, hematuria, nausea and vomiting. The differentials include: nephrolithiasis, pyelonephritis, renal infarct, renal cell carcinoma, pelvic inflammatory disease, ovarian torsion, testicular torsion, prostatitis, prostatic cancer, ectopic pregnancy, orchitis, appendicitis, cholecystitis, ischemic colitis, peptic ulcer disease, portal vein thrombosis, diverticulitis, abdominal aortic aneurysm.
Epidemiology and Demographics
The prevalence and demographic characteristics of renal papillary necrosis depend on the causative agent.*Renal papillary necrosis due to analgesic abuse is more prevalent in Australia and England and less in the US. The prevalence of renal papillary necrosis was reported 65,000 per 100,000 patients with sickle cell disease.In developing countries, the incidence of renal papillary necrosis is 3900 per 100,000 persons.The prevalence of renal papillary necrosis increases with age. It commonly affects the elderly (>60 years).Renal papillary necrosis due to sickle cell disease commonly affects adults in the third and fourth decades.Renal papillary necrosis is more prevalent in women.
Risk Factors
Natural History, Complications & Prognosis
Common complications of renal papillary necrosis include Kidney infection and stones, chronic renal failure, kidney cancers, hypertension, anemia and ESRD. Prognosis depends on the underlying condition.
Diagnosis
The diagnosis of renal papillary necrosis is made by a history of having high-risk conditions such as analgesic abuse and urinalysis and Ultrasound, CT, or other imaging tests of the kidneys.
History and Symptoms
The most common symptoms of renal papillary necrosis include back pain, fever, bloody urine, presence of tissues in urine, Cloudy urine, dysuria, frequency, urgency and urinary incontinency. History of medical conditions such as diabetes and sickle cell disease and long term analgesics use such as acetaminophen and NSAIDS should be considered. If left untreated or progressed, symptoms of chronic renal failure may be developed.
Physical Examination
Common physical examination findings of renal papillary necrosis include fever, costovertebral angle tenderness, and hematuria.
Laboratory Findings
X-ray
CT Scan
CT urography is helpful in the diagnosis of renal papillary necrosis that shows multiple small accumulations of contrast media in the papillary regions near the calyx system. The lobster claw sign is a diagnostic finding on CT urography in the papillary subtype of renal papillary necrosis that develops due to elongation of the minor calyx fornices following ischemia and destruction of the renal papilla.
MRI
MRI can be used as a helpful alternative imaging test in children suspected renal papillary necrosis. On Magnetic resonance urography, renal papillary necrosis is characterized by classic signs of papillary necrosis including candle-flame appearance, Golf ball on a tee sign, lobster claw sign and clubbing of calyces.
Other Imaging Findings
Biopsy
On renal biopsy, renal papillary necrosis is characterized by necrosis of papilla, swelling and sloughing of papilla, mild inflammation and microcalcification at necrotic area.
Treatment
The mainstay of therapy in renal papillary necrosis is supportive care and treating the underlying cause such as discontinuation of analgesics. In severe cases, dialysis or renal replacement therapy may be required.
Medical Therapy
The mainstay of therapy is supportive care and treating the underlying cause.
Surgery
In severe cases of renal papillary necrosis leading to chronic kidney disease, dialysis or renal replacement therapy may be required.
Prevention
Effective measures for the primary prevention of renal papillary necrosis include controlling underlying diseases such as diabetes or sickle cell anemia, avoid taking over-the-counter analgesics and using the minimum dose of NSAIDs within the shortest time.