The clinical significance of class III (suspicious) urine cytology

Background: Urine cytology, combined with cystoscopy, is the mainstay of the diagnosis and surveillance of urothelial carcinoma (UC). While classes I and II urine cytology are considered benign and classes IV and V are considered malignant the clinical significance of class III urine cytology is unclear. We evaluated the positive predictive value of class III urine cytology for concurrent and subsequent UC. Methods: The records of all class III urine cytology cases during a 3-year period were retrospectively reviewed for the presence of concurrent and subsequent UC, determined by cystoscopy and histological confirmation. Results: Of 111 cases, 54 (48.7%) were associated with concurrent UC and 14 (12.6%) with subsequent UC after an initial evaluation negative for malignancy, with a mean time to diagnosis of 10.8months. Of 27 cases of class III urine cytology with no prior history of UC, 13 (48.1%) had concomitant UC and none had subsequent UC. Of 84 cases of class III urine cytology with a prior history of UC, 41 (48.8%) had a concomitant diagnosis of UC and 14 (16.7%) developed UC during their follow-up, leading to a total of 55 (65.5%) cases of UC. Conclusions: Patients with class III urine cytology and a prior history of UC should undergo a full initial evaluation of their urinary tract, and should be followed vigorously if this evaluation is negative for malignancy. Patients without a prior diagnosis of UC and class III urine cytology should also undergo a full initial evaluation, while further larger studies are needed to elucidate the need for further follow-up in such patients.