The clinical significance of class III (suspicious) urine cytology

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.

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.

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 10.8 months. 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.

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.