A 66-year-old hypertensive smoker undergoes coronary angiography. Three weeks later he has a creatinine of 4.2 mg/dL (baseline 1.3), bluish discoloration of both big toes with intact peripheral pulses, abdominal pain, and absolute eosinophil count of 1400/mm³. Urine sediment is bland with occasional tubular epithelial cells. Which finding best supports the diagnosis?

• A Rapid improvement of creatinine within days of stopping contrast exposure
• B Granulomatous interstitial infiltrate with abundant eosinophils in urine
• C Markedly reduced cortical perfusion on radionuclide scan only
• D Cholesterol clefts with foreign body giant cells on skin or kidney biopsy ✓

Explanation

Cholesterol crystal embolisation typically presents one to four weeks after endovascular instrumentation with a stepwise or stuttering rise in creatinine, livedo reticularis, blue toes with preserved pulses, eosinophilia, low complement, and abdominal symptoms from mesenteric emboli. Biopsy showing biconvex needle-shaped clefts surrounded by giant cells is diagnostic. Eosinophil-rich interstitial nephritis lacks the cutaneous and multi-embolic signs, and creatinine does not improve quickly because crystals continue to migrate.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.