Introduction

Urothelial carcinoma of the bladder presents often morphological features that differ from the urothelial common aspect. Specifically, this parameter may change the therapeutic approach at the time of transurethral resection (TUR). However, data are scarce regarding the concordance of histological variants at TUR using radical cystectomy (RC) features as a reference. The aim of our study was to report incidence of histological variants in TUR and RC and to evaluate the agreement between TUR and RC considering histological variants.

Methods

A total of 779 patients treated with TUR and subsequently with RC and pelvic lymph node dissection between 1990 and 2013 at a single tertiary referral center were included in the study. Patients treated with neoadjuvant chemotherapy were excluded from the study due to the aim of work. Dedicated uropathologists evaluated TUR and RC at the same tertiary referral center. Variant histology classification used in our analyses were: sarcomatoid, small cell, squamous or micropapillary. All the other variants were group together as found in less than 10 patients. Grade agreement was calculated using the Cohen kappa coefficient. Absolute value ranges between 0 and 1, where 0 represents pure chance agreement, and 0.1 to 0.4, 0.4 to 0.75, and 0.75 to 1.0, respectively, represent poor, intermediate, and good agreement. Univariable and multivariable logistic regression evaluated the association between the presence of histological variants at TUR and the risk of incur in adverse pathologic features at RC.

Results

Considering TUR, 213 (27.3%) patients were diagnosed with histological variants. Of these, 2.1% (n=16) were found with sarcomatoid variant, 1.7% (n=13) with small cell, 7.1% (n=55) with squamous, 12.5% (n=97) with micropapillary and 4.1% (n=32) defined as others. Considering RC, 212 (27.2%) patients were diagnosed with histological variants. Of these, 2.1% (n=16) were found with sarcomatoid variant, 1.7% (n=13) with small cell, 3.9% (n=30) with squamous, 10.2% (n=78) with micropapillary. Cohen kappa concordance was used to analyze agreement between TUR and RC considering histological variants. In general, poor agreement was found considering micropapillary variant and the presence of an histological variant in general (0.11 and 0.27, respectively). On the other hand, intermediate agreement was found analyzing the presence of sarcomatoid, small cell and squamous variants (0.43, 0.61 and 0.61, respectively). At multivariable analyses, none of the histological variants evaluated at TUR were found to be associated to adverse pathologic stage or node positive disease at RC (all p>0.06). Conversely diagnosis of small cell carcinoma at TUR was found associated with an increased risk of harboring positive STSM (Odds ratio:2.08, confidence interval:1.27-3.41, p=0.03).

Conclusions

The presence of histological variants is a common finding in BCa patients. However, considering this aspect we found poor concordance between TUR and RC. Our findings highlight the necessity of developing new biomarkers to increase the diagnostic value of TUR which may change the therapeutic indication for RC or the necessity of neoadjuvant treatment.

Funding

none