On the Cover

What’s the diagnosis? A 61-year-old man in generally excellent health was referred to the nephrology service with a 10-year history including 8 episodes of recurrent right-sided ureteric colic. Multiple renal stones were submitted for analysis but failed to show any crystalline debris, and were reported as “organic material.” The most recent was called a “gelatinous plug” that demonstrated keratinized debris with some calcium oxalate crystals. Renal imaging studies including ultrasound and computed tomography scanning were reported as normal and specifically no calcifications of the kidney parenchyma or ureter. At nephrology consultation, review of a prior computed tomography study showed a previously unrecognized right calyceal-filling defect. The patient was referred to urology for evaluation. Cystourethroscopy with bilateral pyelography was subsequently performed. The left calyx was normal, but the right kidney demonstrated a calyceal-filling defect. On flexible ureteroscopy, two discrete masses (photographs) were detected within the right renal pelvis. A biopsy was performed. The pathological diagnosis was cholesteatoma without evidence of squamous cell carcinoma, melanoma or other type of malignancy (histologic image). At two-month follow-up, laser ablation of the cholesteatoma was performed by ureteroscopy. Renal cholesteatoma is a rare benign condition with only a few cases reported. Recurrent renal colic is a common presenting feature with passage of desquamated tissue. The risk for recurrence or malignant transformation is unknown. (Images and text provided by Henry Mroch, MD, Providence Health Care, Washington State University, Elson S. Floyd College of Medicine, University of Washington; Raymond Lance, MD, Urologic Oncology, Spokane Urology; Michele Rooney, MD, InCyte Pathology, Spokane, Washington; Katherine Tuttle, MD, Providence Health Care, Division of Nephrology, University of Washington)