Bladder Cancer Pathology

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.