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Pathology
- 90 percent of lesions are TCC, 5-9 percent of lesions squamous cell and 1-2 percent of lesions adenocarcinoma.
- Urothelial carcinoma is the most common malignancy of the urinary tract and is the second most common cause of death among genitourinary tumors.
- At initial presentation, 80% of urothelial tumors are non–muscle invasive
- There are multiple growth patterns of urothelial cancer, including flat carcinoma in situ (CIS), papillary tumors that can be low or high grade, and sessile tumors with a solid growth pattern.
- Non–muscle-invasive cancers can be very large because of lack of genetic alterations required for invasion.
- Invasive tumors can be quite small if early genetic changes occur within the tumor cell, allowing for an invasive phenotype.
- Primary TCC with metaplastic elements is not uncommon.
- Cytologic grade adds some independent prognostic information by interpretation on a 1-3 scale is less uniform.
- Tumor stage is the predominant factor in prognostic outcome.
Epithelial dysplasia. Dysplasia exhibits irregular urothelial and nuclear changes in a gradation toward carcinoma. High-grade dysplasia is difficult to distinguish from CIS.
- This is distinct from atypia, which is defined as an increase in cell layer number without changes in tissue structure or nuclear appearance.
- Carcinoma in situ. Urothelial dysplasia has abnormal cytologic and nuclear changes that are preneoplastic but are not sufficient to be characterized as CIS.
- Similar to high grade dysplasia, yet lacks polarity and cell adhesion.
- Probable progenitor of muscle invasive disease.
- Superficial disease Papillary or nodular lesions confined to the mucosa [Ta] constitute true superficial disease.
- Lesions invading the lamina propria [T1] have a significantly higher chance of recurrence and progression [30-40 percent]. They require aggressive treatment and close observation.
Muscle invasive disease
- True involvement of the detrusor which can appear nodular or tentacular. Generally all of high cytologic grade.
- Squamous cell. Secondary to chronic irritation. Stone disease and chronic cathers as well as schistosomiasis infection.
- Adenocarcinoma. Rare lesions. Likely urarchal origin when at bladder dome. Must rule out metastatic deposit from another primary site such as breast or colon.
- Sarcoma. Rare in adults. Embryonal rhabdomyosarcoma seen in infants and young children.
- Small cell carcinoma. Rare lesions with neuroendocrine features. Generally very aggressive clinical course.
References
- Epstein JI, Amin MB, Reuter VR, Mostofi FK: The World Health Organization/International Society of Urological Pathology consensus classification of urothelial (transitional cell) neoplasms of the urinary bladder. Bladder Consensus Conference Committee. Am J Surg Pathol 1998; 22(12):1435-1448.
- Lopez-Beltran A: Bladder cancer: clinical and pathological profile. Scand J Urol Nephrol Suppl 2008; 218:95-109.
- Montironi R, Lopez-Beltran A: The 2004 WHO classification of bladder tumors: a summary and commentary. Int J Surg Pathol 2005; 13(2):143-153.
- Sauter G, Algaba F, Amin A, et al: Nonivasive urothelial neoplasias: WHO classification of noninvasive papillary urothelial tumors. In: Eble J, Sauter G, Epstein JI, Sesterhenn I, ed. World Health Organization classification of tumors, Lyon (France): IARC Press; 2004.
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