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WHO classification


Editor-in-Chief: Debra L. Zynger, M.D.
Maria Tretiakova, M.D., Ph.D.

Last author update: 21 April 2020
Last staff update: 4 April 2023

Copyright: 2003-2023, PathologyOutlines.com, Inc.

PubMed Search: Urothelial tract tumors WHO classification

Maria Tretiakova, M.D., Ph.D.
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Table of Contents
Definition / general | WHO (2016) | Diagrams / tables | Major updates | Histological variations and provisional entities of urothelial carcinoma NOT included in the current WHO classification | Additional references | Board review style question #1 | Board review style answer #1
Cite this page: Tretiakova M. WHO classification. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladderwhoisup.html. Accessed September 25th, 2023.
Definition / general
  • This classification (WHO 2016) is applicable to tumors that occur throughout the urothelial tract including the bladder, ureter, renal pelvis and urethra
  • Urothelial carcinoma (UC) is the most common malignant neoplasm of the urothelial tract
    • High propensity for divergent differentiation and variant morphologies
WHO (2016)
    Urothelial carcinoma ICD-O
  • Infiltrating urothelial carcinoma 8120/3
  • Urothelial carcinoma with divergent differentiation
    • With squamous differentiation
    • With glandular differentiation
    • With trophoblastic differentiation
  • Nested urothelial carcinoma (including large nested variant)
  • Microcystic urothelial carcinoma
  • Micropapillary urothelial carcinoma 8131/3
  • Lymphoepithelioma-like urothelial carcinoma 8082/3
  • Plasmacytoid / signet ring / diffuse urothelial carcinoma
  • Sarcomatoid urothelial carcinoma 8122/3
  • Giant cell urothelial carcinoma 8031/3
  • Poorly differentiated urothelial carcinoma 8020/3
  • Lipid rich urothelial carcinoma
  • Clear cell (glycogen rich) urothelial carcinoma

Noninvasive urothelial lesions
  • Urothelial carcinoma in situ 8120/2
  • Noninvasive papillary urothelial carcinoma, low grade 8130/2
  • Noninvasive papillary urothelial carcinoma, high grade 8130/2
  • Papillary urothelial neoplasm of low malignant potential 8130/1
  • Urothelial papilloma 8120/0
  • Inverted urothelial papilloma 8121/0
  • Urothelial proliferation of uncertain malignant potential
  • Urothelial dysplasia

Squamous cell neoplasms
  • Pure squamous cell carcinoma 8070/3
  • Verrucous carcinoma 8051/3
  • Squamous cell papilloma 8052/0

Glandular neoplasms
  • Adenocarcinoma, NOS 8140/3
    • Enteric 8144/3
    • Mucinous 8480/3
    • Mixed 8140/3
  • Villous adenoma 8261/0

    Urachal carcinoma 8010/3

Tumors of Müllerian type
  • Clear cell carcinoma 8310/3
  • Endometrioid carcinoma 8380/3

Neuroendocrine tumors
  • Small cell neuroendocrine carcinoma 8041/3
  • Large cell neuroendocrine carcinoma 8013/3
  • Well differentiated neuroendocrine tumor 8240/3
  • Paraganglioma 8693/1

Melanocytic tumors
  • Malignant melanoma 8720/3
  • Nevus 8720/0
  • Melanosis

Mesenchymal tumors
  • Rhabdomyosarcoma 8900/3
  • Leiomyosarcoma 8890/3
  • Angiosarcoma 9120/3
  • Inflammatory myofibroblastic tumor 8825/1
  • Perivascular epithelioid cell tumor
    • Benign 8714/0
    • Malignant 8714/3
  • Solitary fibrous tumor 8815/1
  • Leiomyoma 8890/0
  • Hemangioma 9120/0
  • Granular cell tumor 9580/0
  • Neurofibroma 9540/0

Urothelial tract hematopoietic and lymphoid tumors

Miscellaneous tumors
  • Carcinoma of Skene, Cowper and Littre glands 8140/3
  • Metastatic tumors and tumors extending from other organs
  • Epithelial tumors of the upper urinary tract
  • Tumors arising in a bladder diverticulum
  • Urothelial tumors of the urethra
Diagrams / tables

Images hosted on other servers:

Infiltrating urothelial carcinoma

Major updates
  • New / renamed entities: poorly differentiated urothelial carcinoma - replaced undifferentiated urothelial carcinoma encompassing broad spectrum of poorly differentiated tumors including those with osteoclast-like giant cells, with mixed morphologies and undifferentiated phenotype
  • Removed entities: lymphoma-like urothelial carcinoma (now part of plasmacytoid urothelial carcinoma)
  • Refined morphologic and immunohistochemical criteria for the diagnosis of urothelial carcinoma variants and divergent differentiation:
    • Divergent differentiation occurs in a background of conventional urothelial carcinoma
    • Nested urothelial carcinoma: described large nested variant
    • Plasmacytoid urothelial carcinoma: clarified morphologic criteria in plasmacytoid urothelial carcinoma with signet ring cells as not associated with extracellular mucin production, unlike a true signet ring cell adenocarcinoma
    • Micropapillary urothelial carcinoma:
      • Diagnosis restricted to invasive component only
      • No specific threshold (percentage of presence) to classify
      • Refined morphologic criteria based on highest interobserver reproducibility: multiple nests in the same lacunar space
  • Distinct molecular alterations in some of urothelial carcinoma variants:
    • Micropapillary urothelial carcinoma: common HER2 / neu amplifications or mutations
    • Plasmacytoid urothelial carcinoma: loss of E-cadherin and CDH1 gene loss of function mutations or methylation
    • No significant association with Epstein-Barr virus (EBV) or human papillomavirus (HPV) infection and urothelial carcinoma development
  • Prognostic implications of the urothelial carcinoma variants:
    • Worse prognosis / more aggressive behavior associated with micropapillary and plasmacytoid urothelial carcinoma variants
    • Uniformly poor prognosis for sarcomatoid, poorly differentiated and giant cell urothelial carcinoma
    • Nested variant, lipid rich and urothelial carcinoma with divergent differentiation (squamous, glandular or trophoblastic) are more likely to present with advanced disease but when adjusted by stage had no survival differences with respect to conventional urothelial carcinoma
Histological variations and provisional entities of urothelial carcinoma NOT included in the current WHO classification
  • Urothelial carcinoma, inverted growth (inverted papilloma-like)
  • Pseudoangiosarcomatous (angiosarcoma-like) urothelial carcinoma
  • Urothelial carcinoma with myxoid stroma / chordoid features
  • Urothelial carcinoma with rhabdoid features
  • Urothelial carcinoma with unusual stromal reactions
    • Pseudosarcomatous stroma
    • Stromal osseous metaplasia
    • Stromal cartilaginous metaplasia
    • Osteoclast-like giant cells
    • Prominent lymphoid infiltrate
  • Urothelial carcinoma in specific clinical setting
    • Urothelial carcinoma in augmentation cystoplasty
    • Urothelial carcinoma in neurogenic bladder (spinal cord injury)
    • Urothelial carcinoma in children and young adults
Board review style question #1
Which of the following tumors demonstrate invasion (tumor beyond the basement membrane)?

  1. Infiltrating urothelial carcinoma
  2. Inverted urothelial papilloma
  3. Papillary urothelial neoplasm of low malignant potential
  4. Urothelial carcinoma in situ
  5. Urothelial papilloma
Board review style answer #1
A. Infiltrating urothelial carcinoma

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Reference: World Health Organization (WHO) 2016 classification of urothelial tract tumors
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