UPPER URINARY TRACT CHOLESTEATOMA MISDIAGNOSED AS A URETERAL TUMOR

Abstract

Cholesteatoma of the upper urinary tract is a rare nonmalignant condition histologically characterized by keratinizing desquamative squamous metaplasia. Cholesteatoma has microscopic features of squamous metaplasia of the transitional epithelium and keratinization. These changes with subsequent desquamation of the superficial epithelial layers explain clinical manifestations of the disease. Flank pain, passage of cornified material in the urine and a filling defect on excretory urography (IVP) constitute the characteristic triad. Most cases are managed by extensive ablative surgery due to the potential for malignancy. A 60-year-old woman presented with a 3-year history of intermittent right flank pain in September 1999. These episodes recurred at 3 to 4-month intervals, and the pain was sometimes colicky. Medical history included hypertension and transabdominal hysterectomy for uterine myoma in 1992. Physical examination was unremarkable. Urine microscopy revealed hematuria. Urine cultures, including cultures for acid-fast bacilli, were negative. Serum blood urea nitrogen and creatinine were normal. Plain abdominal radiographs showed multiple linear calcification in the right 4th lumbar paravertebral area. IVP revealed a coarse linear filling defect in the calcified area of the proximal ureter and ureteral dilatation proximal to the involved area. A right retrograde pyelogram demonstrated a large filling defect in the proximal ureter with focal segmental narrowing and dilatation just distal to the involved area. This configuration resembled the “goblet sign” often associated with ureteral tumors (fig. 1). Computerized tomography showed right hydronephrosis with a focal filling defect in the right renal pelvic area and 1 3 1 3 5 cm. calcified mass in the right proximal ureter. Urine cytology demonstrated a moderate number of benign squamous cells and a few suspicious cells. From these findings we could not rule out a ureteral tumor. Right nephroureterectomy with bladder cuffing was done. The specimen showed a dilated pelvicaliceal system filled with whitish keratinous material extending into the proximal ureter. The mass was attatched loosely to the mucosa of the renal pelvis (fig. 2). Microscopically, there was keratinizing desquamative squamous metaplasia of the mucosa of the renal pelvis with marked keratinized debris in the renal pelvis and proximal ureter.