Clinicopathologic analysis of patients undergoing repeat transurethral resection of bladder tumour following an initial diagnosis of urothelial carcinoma with lamina propria invasion and variant/divergent histology.

Aims: A subset of patients with urothelial carcinoma (UCa) and lamina propria (LP) invasion in bladder biopsies/transurethral resections (TURs) are at significant risk for recurrence and have increased rates of progression to UCa with muscularis propria (MP) invasion. The clinicopathologic features of this patient population has not been well characterised in the Pathology literature.

Methods: We performed a search through our urologic pathology files and expert consult cases of the senior author for bladder biopsies/TURs of UCa with LP invasion and variant/divergent histology from 2014 to 2020. Patients with a prior diagnosis of UCa with MP invasion or upper tract UCa were excluded. Clinicopathologic data were obtained.

Results: Ninety-five patients with at least one biopsy/TUR of UCa with LP invasion and variant/divergent histology were identified. Mean patient age was 72 years (range: 46-92 years) with a male predominance 2.3:1. Initial variant/divergent histologies identified were: glandular (35.8%), squamous (23.2%), micropapillary (20%), clear cell/lipid rich (12.6%), diffuse/signet ring/plasmacytoid (10.5%), nested (9.5%), sarcomatoid (6.3%), poorly differentiated/anaplastic (4.2%), small cell (2.1%), lymphoepithelioma-like (2.1%), osteoclast-like giant cells (1.1%) and tumour giant cells (1.1%). Two or more variant histologies were identified in 18.9% of these cases. The rate of micropapillary UCa was significantly higher in multifocal tumours compared with unifocal tumours (37% vs 7.1%).

Conclusions: In our cohort of patients undergoing early repeat biopsy/TUR, 75% of patients had persistent UCa. Additionally, almost 25% of patients had a prior diagnosis of UCa without a variant/divergent histology identified. Our findings highlight the critical role of repeat biopsy/TUR especially in a subset of patients who have variant/divergent histology, even in the absence of MP invasion.