Typically in invasive papillary urothelial carcinoma both the overlying papillary and the invasive components are high grade.
Researches have described a series of patients with invasive low-grade papillary urothelial carcinoma ( LPUC ) in which both the non-invasive and invasive components are low grade.
A retrospective search from The Johns Hopkins Surgical Pathology Database and consult cases from one of the author's files from 1998 to 2011 found 54 cases of invasive low-grade papillary urothelial carcinoma, excluding the more common, unique, and already well-characterized nested variant of urothelial carcinoma.
Slides were available for 41 cases and formed the basis of the current study.
The mean patient age was 68.4 years, with a male predominance.
The specimens consisted of 37 bladder biopsies, 1 renal pelvis biopsy, 1 cystoprostatectomy specimen, 1 nephrectomy specimen, and 1 nephroureterectomy specimen.
In all cases, invasion was limited to the superficial lamina propria above the muscularis mucosae. None of the histologic features correlated with tumor recurrence.
Follow-up information was available for 73% of cases, with an average time interval of 49 months. Recurrent tumor was identified in 10/29 ( 34% ) cases; however, 34% of cases without recurrence had limited follow-up ( less than 24 months ).
Three patients showed progression in tumor grade, and 3 additional patients progressed in both grade and stage ( 60% stage / grade progression ).
Four patients developed recurrence with ureteral noninvasive low-grade papillary urothelial carcinoma ( 2 in the bladder and 2 in the ureter ).
All are alive without disease.
As this lesion is being increasingly recognized, larger studies are needed to determine whether invasion arising in low-grade papillary urothelial carcinoma is a significant risk factor for future disease. ( Xagena )
Toll AD, Epstein JI, Am J Surg Pathol 2012;36:1081-1086