154P - Can urine cytology predict variants of bladder cancer?

Background

The variants of urothelial carcinoma such as micropapillary (MP), plasmacytoid (PC), and lipid cell (LC) carry a very poor prognosis. High progression speed and resistance to chemotherapy are considered to be part of the reasons for poor prognosis. Accordingly, early diagnosis and early treatment are important to improve prognosis. In this study, we elucidated the cytological diagnostic criteria of these variants, and also investigated whether preoperative urine cytology could diagnose these variants and the possible association between cytological predictability and pathological features.

Methods

Between April 2015 and March 2020, 45 patients were histologically diagnosed as MP, PC, and LP by TURBT in our institution. The experienced cytologists (YW) in our hospital re-evaluated the preoperative urine cytology in these cases to determine whether or not the prediction of the variant histology is possible. The following findings were used as criteria, small papillary cell clumps with strong binding in MP, circular atypical cells similar to plasma cells in PC, and atypical cells similar to lipoblasts with empty cells in LC. Additionally, we analyzed whether histopathological findings such as muscle invasion, tumor size, tumor necrosis, lymphovascular invasion (LVI), CIS, affect the prediction of the variants.

Results

Of 45 cases, MP, PC and LC were 18 (40%), 13 (29%) and 14 (31%) patients, respectively. 3 cases of MP (17%), 5 of PC (38%) and 2 of LC (14%) could be predicted by re-evaluating preoperative urine cytology. In addition, positive preoperative urine cytology (class 4 or higher) was found in 14 cases in MP (78%), 8 cases in PC (62%), and 11 cases in LC (79%), with estimated probabilities of 21%, 62%, and 18%, respectively. Pathological features were not different between the predictable and unpredictable cases: muscle invasion, 90% vs 74% (P = 0.26); median tumor size, 31 mm vs 38 mm (P = 0.37); tumor necrosis, 20% vs 28% (P = 0.64); LVI, 60% vs 45% (P = 0.42); CIS, 40% vs 34% (P = 0.74), respectively.

Conclusions

Although in some cases, atypical cells suggesting UC variants appeared in the urine cytology, this study suggested that the preoperative cytological diagnosis of bladder cancer variants seems to be difficult.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.