Kidney tumor
Adult renal cell carcinoma
Urothelial carcinoma of renal pelvis - microcystic variant

Author: Nicole K. Andeen, M.D.
Editor: Maria Tretiakova, M.D.

Revised: 19 April 2018, last major update December 2015

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Urothelial carcinoma microcystic

Related Topic: Urothelial carcinoma of renal pelvis
Page views in 2018: 148
Page views in 2019 to date: 86
Cite this page: Andeen, N.K. Microcystic variant. website. Accessed July 18th, 2019.
Definition / general
  • Invasive urothelial carcinoma with deceptively bland architecture and cytology, consisting of slit-like or tubular microcysts lined by cuboidal / flattened cells with minimal atypia and intraluminal granular eosinophilic material (Mod Pathol 2009;22:S96)
  • Given overall rarity and similarities with microcystic urothelial carcinoma of the bladder, some information and pictures are extracted from bladder, where appropriate
Essential features
  • Very rare
  • Main biologic significance is deceptively benign features, which may be mistaken for cystitis cystica or glandularis on small biopsies, but is usually deeply invasive
  • Histologically may be distinguished by infiltrative growth pattern and variability in cyst size / shape
  • < 20 cases reported in genitourinary tract including 3 in renal pelvis
  • Bladder, renal pelvis
Clinical features
  • Usually deeply invasive
Prognostic factors
Case reports
  • No consensus established
Microscopic (histologic) description
  • Invasive urothelial carcinoma with slit-like or tubular microcysts, lined by single to multilayered cuboidal or flattened cells with minimal cytologic atypia
  • Microcysts are irregular in size / shape, and deeply infiltrative
  • Has luminal granular eosinophilic secretions with necrotic cellular debris, sometimes mucinous material or a targetoid appearance (PAS+, Alcian blue+) (Mod Pathol 2009;22:S96, Arch Pathol Lab Med 2007;131:1244)
  • May be focally calcified
  • May be associated with nested variant of urothelial carcinoma
Microscopic (histologic) images

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Cysts of various sizes

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Neoplastic cystic structures

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Cuboidal or flattened cells

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Eosinophilic secretions

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Low grade UC

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Microcystic variant

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Deceptively bland urothelial carcinoma composed of infiltrative, microcystic/tubular structures

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Deep muscular invasion

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CK7 highlights invasive nests

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Microcystic and nested features

Positive stains
Negative stains
Differential diagnosis
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