Urine cytology is a feasible tool for assessing erythematous bladder lesions after bacille Calmette-Guérin (BCG) treatment.

OBJECTIVES: To investigate the need to biopsy erythematous lesions of the bladder after bacille Calmette-Guérin (BCG) treatment as well as the diagnostic value of voided urine cytology in the detection of recurrence.

MATERIALS AND METHODS: Data on 206 consecutive patients with non-muscle-invasive bladder cancer treated with one or more BCG instillations in the period 2009-2015 at Satakunta Central Hospital and Turku University Hospital were reviewed. Biopsy histology was pooled according to lesion cystoscopy appearance regarding growth pattern and presence of erythema. Voided urine cytology grading before resection was reviewed. We correlated the cystoscopy findings with histology and calculated the sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) for voided urine cytology.

RESULTS: In total, 159 patients with a median follow-up of 35 months were included in the study. Altogether, 367 biopsies were analysed. In the case of papillary or flat tumours, 76% of biopsies showed malignant histology and the diagnostic value of cytology was very limited (sensitivity 33%, specificity 84%). Erythematous lesions constituted 57% of all biopsy targets, with the majority being either chronic non-specific inflammation or granulomatous inflammation; 10% of erythematous lesions were malignant at pathological examination. In contrast to papillary and flat tumours, cytology proved to be more accurate in the case of erythematous lesions with a sensitivity, specificity, PPV and NPV of 59%, 76%, 23% and 94%, respectively.

CONCLUSION: Bladder lesions after BCG instillations pose a challenge during follow-up and the appropriate management strategy is not clear. Lesions should not be overlooked as being BCG-induced irritation because they may harbour significant malignancies. The presence of papillary or flat tumour always warrants a biopsy or resection. In the case of erythematous lesions, our results suggest that biopsy may be avoided if voided urine cytology is negative.