The Influence of Inverted Growth Pattern on Recurrence for Patients with Non-Invasive Low Grade Papillary Urothelial Carcinoma of Bladder

Abstract

Aims:To evaluate the impact of a histologically inverted pattern on recurrence in patients with newly diagnosed non-invasive, low-grade papillary urothelial carcinoma of the urinary bladder.Methods:A total of 81 patients with primary bladder non-invasive, low-grade papillary urothelial carcinoma diagnosed in a single tertiary-care centre who had at least 1-year follow-up after an initial resection were included. All slides from each case were reviewed to determine the growth pattern (exophytic versus endophytic, i.e. inverted) and other histological parameters. Clinical data were retrieved from hospital records.Results: Disease recurrence occurred in 41 (50.6%) patients. Cases with an inverted pattern showed a lower recurrence rate than those with pure exophytic tumours (37.5% versus 52.1%), a longer time to first recurrence (mean 34 versus 21.5 months) and fewer recurrence episodes (p=0.482, 0.564 and 0.051, respectively). All recurring inverted cases recurred only once during follow-up. No tumour with >80% inverted architecture recurred.Conclusion:Our results suggest that non-invasive, low-grade papillary urothelial carcinoma of the bladder tends to have a better outcome in terms of disease recurrence if it shows an inverted growth pattern. To indicate the presence and percentage of the inverted pattern in low-grade urothelial carcinomas in the pathology report might be considered as an adjunct to help long-term patient management.

Clinicopathologic Features of Noninvasive Inverted Urothelial Papillary Tumor

“…Those with inverted tumors showed a lower recurrence rate (37.5% vs. 52.1%, P = 0.482), a longer interval to first recurrence (mean: 34 vs. 21.5 mo, P = 0.564), and fewer recurrence episodes (P = 0.051) than those with exophytic tumors. 19 Maxwell and colleagues found a 20.1% recurrence rate among 189 primary PUNLMPs after median follow-up of 61 months. Progression to low-grade carcinoma occurred in 9.5% and to high grade in 1.6% of patients but no recurrence or progression was reported for those tumors demonstrating purely inverted growth.…”

“…Three IPUNLMP patients had recurrent PUNLMP (inverted or exophytic) and 7 L/HG-PUCI patients had recurrent LG-PUC or HG-PUC (inverted or exophytic). Three of 19 LG-PUCI patients (15.8%) had subsequent recurrence: 1 case progressed to high-grade carcinoma and 2 cases recurred as low-grade only. Four of 5 HG-PUCI patients (mainly high-grade) had a subsequent recurrence of low-grade or high-grade carcinomas.…”

Case of inverted papillary urothelial carcinoma in the ureter

“…Unlike urothelial carcinoma, IP does not warrant frequent long‐term follow‐up because it is considered to be a benign tumor and not a risk factor for the occurrence of urothelial carcinoma 2,10 . However, the risk of invasiveness and recurrence of IPUC is estimated to be similar to that of exophytic papillary cancer 11 . Despite the difficulty in distinguishing between IP and IPUC histologically, 12,13 the distinction is important because the biologic behavior of these entities is very different, as is their treatment.…”

The Genitourinary Pathology Society Update on Classification and Grading of Flat and Papillary Urothelial Neoplasia With New Reporting Recommendations and Approach to Lesions With Mixed and Early Patterns of Neoplasia

“…All recurring inverted cases recurred only once, and no tumor with > 80% inverted growth pattern recurred. 107 Recently, one of the largest studies to date of invasive high-grade urothelial carcinoma arising in a background of urothelial carcinoma with an inverted growth pattern (91 cases) also highlighted potential pitfalls. In this study, 20% of the patients that had invasive high-grade urothelial carcinoma of the bladder arising in a background of urothelial carcinoma with an inverted growth pattern developed metastasis, and 26% died of disease, emphasizing the importance of the identification of invasive foci and variant/ divergent morphology.…”