Page 502 - Concise Pathology for Exam Preparation ( PDFDrive )

16 Diseases of the Kidney and Lower Urinary Tract 487

Q. Write briefly on urothelial (transitional cell) tumours.

Ans. Tumours of urinary bladder include
1. Urothelial (transitional cell) tumours
(a) Exophytic papilloma
(b) Inverted papilloma
(c) Papillary urothelial neoplasms of low malignant potential
(d) Low-grade and high-grade papillary urothelial cancers
(e) Carcinoma in situ (CIS or flat non-invasive urothelial carcinoma)
2. Mixed carcinoma
3. Adenocarcinoma
4. Small cell carcinoma
5. Sarcomas
WHO grading of urothelial (transitional cell) tumours is given in Table 16.14.

TABLE 16.14. Grading of urothelial (transitional cell) tumours of the urinary bladder
WHO grading
Urothelial papilloma
Papillary urothelial neoplasms of low malignant potential
Low- or high-grade papillary urothelial cancers
Carcinoma in situ (CIS or flat non-invasive urothelial cancers

Peak Age

50–80 years

Gender Distribution
Male:female ratio = 3:1

Pathogenesis

Tumours arising from urothelium are known to be associated with the following:
• Cigarette smoking
• Industrial exposure to aryl amines
• S. haematobium infection
• Long-term use of analgesics
• Long-term exposure to cyclophosphamide
• Monosomy of chromosome 9
• Deletions of 9p and 9q as well as deletions of 17p, 13q, 11p and 14q
• 9p deletions (9p21) involve the tumour-suppressor gene p16 (MTS 1 and INK 4 alfa,
which encodes an inhibitor of a cyclin-dependent kinase and also the related p15

Morphology
• Exophytic papillomas are small pedunculated lesions composed of a connective tissue
stalk covered by normal appearing urothelium.
• Inverted papillomas show bland appearing epithelium extending down into the lamina
propria.
• Papillary urothelial neoplasms of low malignant potential differ from a papilloma in
having a thicker urothelial layer.
• Low-grade papillary urothelial carcinomas show mild atypia and increased mitoses but
have an orderly architecture and maintain nuclear polarity. They may infrequently recur
or rarely invade.

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