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Urothelial tumors

WHO / ISUP classification (2004)

Reviewer: Monika Roychowdhury, M.D., University of Minnesota Medical Center (see Reviewers page)
Revised: 6 May 2011, last major update May 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.


World Health Organization / International Society of Urologic Pathologists consensus classification (Am J Surg Pathol 1998;22:1435), republished with no major changes in 2004 (Pathol Int 2010;60:1, Eble: Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs, 2004)
● Major changes from prior systems are that papillary urothelial carcinomas must exhibit atypia, and that carcinoma in situ need not be full thickness
● WHO/ISUP grade correlates with tumor stage and recurrence
● Has been validated for prognostic variables (Am J Clin Pathol 2010;133:788), and by differences in CK20, p53 and Ki-67 staining (Am J Clin Pathol 2004;121:679)
● Criticisms include (a) no increase in reproducibility for low grade tumors over 1973 WHO classification (Virchows Arch 2003;443:734), (b) no definite improvement over other grading systems (J Clin Pathol 2002;55:900), (c) not useful for predicting clinical outcome in invasive urothelial carcinoma (Mod Pathol 2009;22:S70)
References: Presentation by Dr. Mahul Amin-2004

Prior Classification systems

Ash (1940):
● Classified as transitional cell carcinoma grades 1-4
● Grade 1 comparable to papilloma
● Grade 2 comparable to low grade
● Grade 3 (most) and grade 4 comparable to high grade

Mostofi (1960):
● Grade 1 called papilloma and not carcinoma

WHO / ISUP classification of urothelial lesions (1998)

Note: each entity is described as a separate topic in the Bladder chapter

● Flat mucosa with no overt thickness
● Includes slight disorganization of cells and nuclear pleomorphism, formerly termed mild dysplasia; size of normal urothelial cells is 3x lymphocytes

● Flat hyperplasia, papillary hyperplasia

Flat lesions with atypia:
● Reactive (inflammatory) atypia, atypia of unknown significance, dysplasia (LG IUN), CIS (HG IUN)

Papillary urothelial neoplasms:
● Papilloma, inverted papilloma, papillary neoplasm of low malignant potential, noninvasive papillary carcinoma-low grade, noninvasive papillary carcinoma-high grade

Invasive urothelial neoplasms:
● Lamina propria invasion, muscularis propria (detrusor muscle) invasion

Low grade neoplasms:
● Includes papilloma, inverted papilloma, papillary neoplasm of low malignant potential, low grade papillary urothelial neoplasms, urothelial carcinoma grade 1 of 3, some urothelial carcinomas grade 2 of 3

WHO / ISUP classification of tumors of urinary tract (2004)

Urothelial tumors
Infiltrating urothelial carcinoma 8120/3
● with squamous differentiation
● with glandular differentiation
● with trophoblastic differentiation
● Nested
● Microcystic
● Micropapillary 8131/3
● Lymphoepithelioma-like 8082/3
● Lymphoma-like
● Plasmacytoid
● Sarcomatoid 8122/3
● Giant cell 8031/3
● Undifferentiated 8020/3

Non-invasive urothelial neoplasias
● Urothelial carcinoma in situ 8120/2
● Non-invasive papillary urothelial carcinoma, high grade 8130/2 or 3
● Non-invasive papillary urothelial carcinoma, low grade 8130/2 or 1
● Non-invasive papillary urothelial neoplasm of low malignant potential 8130/1
● Urothelial papilloma 8120/0
● Inverted urothelial papilloma 8121/0

Squamous neoplasms
● Squamous cell carcinoma 8070/3
● Verrucous carcinoma 8051/3
● Squamous cell papilloma 8052/0

Glandular neoplasms
● Adenocarcinoma 8140/3
     ● Enteric
     ● Mucinous 8480/3
     ● Signet-ring cell 8490/3
     ● Clear cell 8310/3
● Villous adenoma 8261/0

Neuroendocrine tumours
● Small cell carcinoma 8041/3
● Carcinoid 8240/3
● Paraganglioma 8680/1

Melanocytic tumours
● Malignant melanoma 8720/3
● Nevus

Mesenchymal tumours
● Rhabdomyosarcoma 8900/3
● Leiomyosarcoma 8890/3
● Angiosarcoma 9120/3
● Osteosarcoma 9180/3
● Malignant fibrous histiocytoma 8830/3
● Leiomyoma 8890/0
● Haemangioma 9120/0
● Other

Haematopoietic and lymphoid tumours
● Lymphoma
● Plasmacytoma 9731/3

Miscellaneous tumours
● Carcinoma of Skene, Cowper and Littre glands
● Metastatic tumours and tumours extending from other organs

Note: Four digit numbers are the morphology code from ICD-0 and SNOMED
Behavior is coded as 0-benign, 1-borderline / uncertain, 2-in situ carcinoma / grade III intraepithelial neoplasia or 3-malignant

End of Bladder > Urothelial tumors > WHO / ISUP classification (2004)

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