Targeted sequencing of plasmacytoid urothelial carcinoma reveals frequent TERT promoter mutations.

Activating mutations in the promoter of the telomerase reverse transcriptase (TERT) gene are the most common genetic alterations in urothelial carcinoma (UC) of the bladder and upper urinary tract. Although the cadherin 1 (CDH1) gene is commonly mutated in the clinically aggressive plasmacytoid variant of urothelial carcinoma (PUC), little is known about their TERT promoter mutation status. A retrospective search of our archives for PUC and UC with plasmacytoid and/or signet ring cell features (2007-2014) was performed. Ten specimens from 10 patients had archived material available for DNA analysis and were included in the study. Intratumoral areas of nonplasmacytoid histology were also evaluated when present. Samples were analyzed for TERT promoter mutations with Safe-SeqS, a sequencing error-reduction technology, and sequenced using a targeted panel of the 10 most commonly mutated genes in bladder cancer on the Illumina MiSeq platform. TERT promoter mutations were detected in specimens with pure and focal plasmacytoid features (6/10). Similar to conventional UC, the predominant mutation identified was g.1295228C>T. In heterogeneous tumors with focal variant histology, concordant mutations were found in plasmacytoid and corresponding conventional, glandular, or sarcomatoid areas. Co-occurring mutations in tumor protein p53 (TP53, 2 cases) and kirsten rat sarcoma (KRAS) viral proto-oncogene (1 case) were also detected. TERT promoter mutations are frequently present in PUC, which provides further evidence that TERT promoter mutations are common events in bladder cancer, regardless of histologic subtype, and supports their inclusion in any liquid biopsy assay for bladder cancer.

Significance of a minor high-grade component in a low-grade noninvasive papillary urothelial carcinoma of bladder.

To assess the clinicopathological features and prognostic significance of the presence of 5% or less high-grade component in otherwise low-grade noninvasive bladder urothelial carcinoma, referred to as mixed-grade (MG) urothelial carcinoma, we reviewed all archival cases with such diagnosis between 2005 and 2014. Clinicopathological and outcome parameters were compared to those in our previously reported low- and high-grade noninvasive bladder urothelial carcinoma cohorts (LGUC and HGUC, respectively). The study included 31 MG urothelial carcinomas. Mean patient age was 67.6 years, and mean follow-up was 39.7 months. Intravesical treatment was administered in 15 patients (48.4%). Recurrence occurred in 14 cases (45.2%): 10 as LGUC and 4 as HGUC; there was no stage progression. Mean time to progression was 9 months (5-17 months), and there was no death of disease. MG urothelial carcinoma stage progression and dead of disease rates were comparable to that of LGUC. MG urothelial carcinoma stage progression was significantly lower than that of HGUC, P = .002, using Pearson χ(2) test. MG urothelial carcinoma patients with no intravesical treatment had higher incidence rate of grade progression (25%) compared to LGUC patients (7.9%); however, the difference was not statistically significant. MG urothelial carcinoma had a prognosis closer to "pure" LGUC than "pure" HGUC. Untreated MG urothelial carcinoma may have a higher rate of grade progression than LGUC, although more data are needed before this issue can be definitively addressed. Until such data are available, it is reasonable to keep MG urothelial carcinoma as a distinct grade category with potential management implications.