Ischaemic insult causes coagulative necrosis of renal medullary pyramids and papillae.
May be focal involving the tip of a papilla, or diffuse affecting entire papillae or kidneys.
Can be a chronic, relapsing disease.
Can cause acute obstruction and renal colic. The sloughed papillae may prove a nidus for stone formation, and become necrotic and become a nidus for infection.
May present in a manner similar to pyelonephritis, or renal colic. Patients may also pass material in their urine, or have haematuria.
The renal papilla exist in a relative state of hypoxia even in healthy patients, as the vasa recta which supply papillae have a sluggish flow.
Repeated obstructions can lead to CKD.
Causes (POSTCARDS)
- Pyelonephritis
- Obstruction / obstructive uropathy
- Sickle cell disease
- Tuberculosis
- Cirrhosis or alcoholism
- Analgesics – NSAIDs or phenacetin
- Renal vein thrombosis; renal transplant rejection
- Diabetes
- Systemic vasculitis
Management
Relieve the obstruction if acutely obstructed +/- infected. Treat any underlying cause. Renal physician involvement.
Imaging
- Renal atrophy
- Poorly marginated, hypoattenuated lesions in the region of the papilla
- Contrast filled clefts the renal medulla (“crab claw” “golf ball on tee”)