Pathology Outlines - Urothelial carcinoma of renal pelvis

Kidney tumor
Renal pelvis: Urothelial carcinoma and variants
Urothelial carcinoma of renal pelvis - nested

Senior Author: Maria Tretiakova, M.D., Ph.D.

Topic Completed: 1 October 2015

Revised: 18 September 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Urothelial carcinoma nested variant renal pelvis

Related Topic: Urothelial carcinoma of renal pelvis

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Table of Contents

Cite this page: Andeen NK, Tretiakova M. Urothelial carcinoma of renal pelvis - Nested. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/kidneytumormalignanturothelialcarcinomasubtypesnested.html. Accessed November 16th, 2019.

Definition / general

Morphologic variant of urothelial carcinoma characterized by unusually bland, nested pattern of invasion but with clinical outcomes similar to conventional invasive high grade urothelial carcinoma (Arch Pathol Lab Med 2007;131:1725)

Essential features

Cytologically bland nested pattern that could be difficult to distinguish from Florid von Brunn's nests, but more irregular and often deeply invasive
Clinical outcomes are similar to invasive high grade urothelial carcinoma

Terminology

Given the rarity of nested variant of urothelial carcinoma of the renal pelvis and its morphologic similarity to the bladder site, this review includes pertinent data and images from bladder, where appropriate

Epidemiology

Very rare in kidney, and overall rare in genitourinary tract; only a few hundred cases reported (Adv Urol 2014;2014:192720)
In bladder mean age is 68 years, male predominance (Arch Pathol Lab Med 2007;131:1725), however 3 of 4 cases reported in renal pelvis are in female patients, 49 - 80 years (Pathol Res Pract 2009;205:508, Anal Quant Cytol Histol 2011;33:340, Pol J Pathol 2014;65:74, Urology 2007;69:778.e15)

Sites

Renal pelvis, ureter

Clinical features

Hematuria

Prognostic factors

Data in bladder demonstrates outcomes similar to conventional invasive high grade urothelial carcinoma (Mod Pathol 2003;16:1289)

Case reports

Urothelial carcinoma "nested variant" of renal pelvis and ureter (Urology 2007;69:778.e15)
49 year old woman with pelvic urothelial carcinoma with nested pattern of growth (Anal Quant Cytol Histol 2011;33:340)
54 year old woman with unusual nested carcinoma (Urol Ann 2013;5:287)

Gross description

Thickened, irregular renal pelvis with or without associated papillary component

Gross images

Images hosted on other servers:

Grey white tumor

Microscopic (histologic) description

Anastomosing, irregularly sized nests lacking cytoarchitectural orientation to overlying urothelium, and with more irregular projections into stroma, particularly at deep aspect (Mod Pathol 2009;22:S96)
The overlying urothelium is usually unremarkable
Cytologically bland, usually with focal atypia
Central lumens, which may contain necrotic cellular debris (Stanford University - Surgical Pathology Criteria)
Stroma may be normal or desmoplastic
A component of conventional urothelial carcinoma is present in 64% of cases (Hum Pathol 2010;41:163)

Microscopic (histologic) images

Contributed by Nicole K. Andeen, M.D. and Maria Tretiakova, M.D., Ph.D.

Irregularly sized nests of urothelial cells lacking cytoarchitectural orientation to overlying urothelium and with variable cytologic atypia; some nests show central necrotic debris

Images hosted on other servers:

Urothelial nests

Small, discrete nests

Larger confluent nests

Bland cytologic features

Detrusor muscle invasive

Tubule formation

Anastomosing nests

Irregular ribbons, cords, sheets

Superficial nests

Positive stains

Similar to conventional urothelial carcinomas with CK7, CK20, p63 and CK903 expression in 93%, 68%, 92%, and 92% of cases (Hum Pathol 2010;41:163)
Ki67 variable (2 - 35%) (Mod Pathol 2003;16:1289)

Negative stains

p53, BCL2 usually negative
Loss of p27 expression in deeper component of tumor (Mod Pathol 2003;16:1289)

Molecular / cytogenetics description

Loss of p27, a cyclin dependent kinase inhibitor (p53 independent), may dictate the behavior: loss of p27 has been associated with increased proliferation and progression of disease (Mod Pathol 2003;16:1289)

Differential diagnosis

Florid von Brunn's nests: are relatively round and evenly spaced with uniform linear border at base, vs. nested carcinoma which has anastomosing, smaller irregularly sized nests lacking orientation to overlying urothelium, and more irregular projections into stroma and muscle invasion (Mod Pathol 2009;22:S96)
- Wide variability in staining for Ki67, p53, p27 and CK20 seen in both Florid von Brunn's nests and nested variant of urothelial carcinoma (Am J Surg Pathol 2003;27:1243)
Inverted papilloma: has more cytoarchitectural organization within nests, cells maintain peripheral palisading
Nephrogenic adenoma: may be nested, tubular and have irregular stromal interface but nests are composed of only a single layer of cuboidal or flattened cells and is more likely to contain other architectural patterns (cystic, papillary) and have surrounding stromal edema and inflammatory infiltrate (Mod Pathol 2009;22:S96)
Paraganglioma and carcinoid: characteristic vascular pattern and chromatin features, positive for neuroendocrine markers

Additional references

Advances in Urology 2014;2014:1