Bladder - WHO/ISUP Classification

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Bladder

Urothelial tumors

WHO / ISUP classification (2004)

Reviewer: Andreas Gaumann, Institute of Pathology Kaufbeuren, Germany

Revised: 6 June 2010, last major update June 2010

WHO / ISUP

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● 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 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

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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)

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

Normal:

● 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

Hyperplasia:

● 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)

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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

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