[Significance of TERT promoter mutation in differential diagnosis of non-invasive inverted urothelial lesions of bladder].

Objective: To investigate the gene mutation of telomerase reverse transcriptase (TERT) promoter in inverted urothelial lesions of the bladder and its significance in differential diagnosis. Methods: From March 2016 to February 2022, a total of 32 patients with inverted urothelial lesions diagnosed in Department of Pathology at Qingdao Chengyang People's Hospital and 24 patients at the Affiliated Hospital of Qingdao University were collected, including 7 cases of florid glandular cystitis, 13 cases of inverted urothelial papilloma, 8 cases of inverted urothelial neoplasm with low malignant potential, 17 cases of low-grade non-invasive inverted urothelial carcinoma, 5 cases of high-grade non-invasive inverted urothelial carcinoma, and 6 cases of nested subtype of urothelial carcinoma were retrospectively analyzed for their clinical data and histopathological features. TERT promoter mutations were analyzed by Sanger sequencing in all the cases. Results: No mutations in the TERT promoter were found in the florid glandular cystitis and inverted urothelial papilloma. The mutation rates of the TERT promoter in inverted urothelial neoplasm with low malignant potential, low grade non-invasive inverter urothelial carcinoma, high grade non-invasive inverted urothelial carcinoma and nested subtype urothelial carcinoma were 1/8, 8/17, 2/5 and 6/6, respectively. There was no significant difference in the mutation rate of TERT promoter among inverted urothelial neoplasm with low malignant potential, low-grade non-invasive inverted urothelial carcinoma, and high-grade non-invasive inverted urothelial carcinoma (P>0.05). All 6 cases of nested subtype of urothelial carcinoma were found to harbor the mutation, which was significantly different from inverted urothelial neoplasm with low malignant potential and non-invasive inverted urothelial carcinoma (P<0.05). In terms of mutation pattern, 13/17 of TERT promoter mutations were C228T, 4/17 were C250T. Conclusions: The morphology combined with TERT promoter mutation detection is helpful for the differential diagnosis of bladder non-invasive inverted urothelial lesions.