Ureteritis Cystica: Radiologic-pathologic Correlation

Introduction

Ureteritis cystica (UC) is a rare and benign entity characterized by inflammatory pathology. The entity, first reported by Morgagni in 1761 [1], is a proliferative condition characterized by multiple cysts and filling defects in the urothelium [2]. UC may be associated with chronic urothelial irritation. Some studies have demonstrated causes such as nephrolithiasis [3] and urinary tract infections [4], and it has been found in one patient following instillation of formalin for treatment of cyclophosphamide induced hemorrhagic cystitis [5]. Usually there are no symptoms attributable to UC [2], therefore it is most frequently detected incidentally and the diagnosis is usually made during uretersoscopy or radiographically. Radiographically, a differential diagnosis of multiple transitional cell tumors, ureteral pseudodiverticula, non-opaque calculi, polyps, papillary tumor, vascular impressions, tuberculosis, iatrogenic gas bubbles, gas forming microorganisms, and submucosal hemorrhage can be considered with appropriate clinical correlation. Our patient was a 62-year-old female who was found to have recurrent urinary tract infections (UTI) while being evaluated for hip replacement surgery. Contrast enhanced computed tomography (CT) of her abdomen and pelvis demonstrated bilateral 2 - 3 mm renal calculi. Since the stones were quite small, the patient underwent ureteroscopy for planned treatment of her calculi. A retrograde pyelogram was performed that showed multiple filling defects [Figure 1]. Subsequent ureteroscopic examination showed multiple cystic lesions dispersed throughout the bladder as well as along both ureters and renal pelvises [Figure 2]. A biopsy of the cystic lesion was obtained and it proved to be UC. [Figure 3]. Radiologic Features At intravenous urography or retrograde pyleography, the most common radiologic appearance of UC is that of numerous small, true contour defects of near uniform size, 2 - 3 mm in diameter in the ureter and up to 2 cm in the renal pelvis. The majority of cysts appear hemispherical in shape as opposed to air bubbles that appear round [Figure 1]. Pathologic Features UC manifests as cystic areas of glandular metaplasia associated with chronic urothelial inflammation. The more commonly seen presentation is in the bladder, where they are called cystitis cystica, where the nodules are usually located on the trigone and bladder neck region. Within islands of benign-appearing urothelium are Von Brunn's nests located in the lamina propria. Cystitis cystica occurs when the urothelium in the center of the von Brunn's nests has undergone eosinophilic liquefaction [6]. Microscopic examination of our patient’s ureteral biopsy showed an intact cystic structure lined by benign urothelium with intact umbrella cells, most consistent with cystitis cystica. No goblet cells, dysplasia, or malignancy was seen [Figure 3].

In conclusion, ureteral cystitis, although an incidental diagnosis, should be considered in the differential diagnosis in the presence of small filling defects with a bead-like appearance along the urothelium of the renal pelvis, ureters, and bladder.