Contributors: Stephanie J Conrad, Hongzhi,
A woman in her 60s with a history of COPD, GERD and arthritis presented with a one week history of right flank pain. Work-up revealed an obstructed right kidney with a staghorn calculus and a cystic renal mass. Urine cultures grew E. coli and P. mirabilis.
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1. What is the correct diagnosis?
a. Clear cell renal cell carcinoma
b. Xanthogranulomatous pyelonephritis
c. Mycobacterial infection
d. Spindle cell neoplasm
2. Which of the immunohistochemical stains, when positive, supports the diagnosis?
b. Acid Fast