Micropapillary is currently the most well-studied, independent histology. Although rare relative to the large number of patients with undifferentiated, conventional UC, micropapillary cancer still affects a significant proportion of patients. Here we will review the definitions and implications of micropapillary bladder cancer for those patients with a new diagnosis.
Epidemiology and Statistics 
- 0.7-2.2% of all UC are micropapillary
- Average age at diagnosis: 65
- Male-to-female ratio 10:1
Histology and Pathology [4-8]
- Micropapillary tumors grow in delicate filiform processes in infiltrating clusters lacking vascular stalks (see images from WebPathology.com)
- Vascular and lymphatic invasion is common.
- 80% cases found with conventional UC
- The amount of micropapillary cancer does not have bearing on outcomes; outcomes are consistent if 10% or greater of the tumor contains micropapillary cancer
- Less than 9% have non-muscle invasive disease; 70% will progress to invasive disease.
- At cystectomy for non-muscle invasive disease:
- >50% can be upstaged
- >25% had occult lymph node metastases
- 50% present as muscle-invasive, node-positive or metastatic disease
Treatment and Outcomes
It is clear that micropapillary urothelial cancer is an aggressive variant of bladder cancer; it is unclear if it is independently worse than conventional urothelial cancer.
Therefore, the use of neoadjuvant chemotherapy remains controversial - with some centers advocating its use and some centers believing that neoadjuvant chemotherapy may actually worsen survival by delaying therapy.
Survival Statistics for Micropapillary Cancer of the Bladder
All Patients [11,12,16]
- Overall Recurrence-Free Survival: 58% at 5 years
- Local Recurrence-Free Survival: 62% at 10 years
- Distant Metastases-Free Survival: 44% at 10 years
- Cancer-Specific Survival: 31% at 10 years
- Overall Survival: 40-67% at 5 years, 21% at 10 years
Non-Muscle Invasive Micropapillary Bladder Cancer
Muscle-Invasive Micropapillary Bladder Cancer
1. American Cancer Society, Facts & Figures 2014; Accessed March 21, 2014. http://www.cancer.org/acs/groups/content/@research/documents/webcontent/acspc-042151.pdf
2. Surveillance, Epidemiology, and End Results (SEER) Stat Fact Sheets: Bladder Cancer; Accessed March, 21, 2014. http://seer.cancer.gov/statfacts/html/urinb.html
3. Amin MB, Ro JY, el-Sharkawy T,et al: Micropapillary variant of transitional cell carcinoma of the urinary bladder. Histologic pattern resembling ovarian papillary serous carcinoma. Am J Surg Pathol 1994; 18: 1224-1232.
4. Johansson SL, Borghede G, Holmang S,et al: Micropapillary bladder carcinoma: a clinicopathological study of 20 cases. J Urol 1999; 161: 1798-1802.
5. Kamat AM, Dinney CP, Gee JR,et al: Micropapillary bladder cancer: a review of the University of Texas M.D. Anderson Cancer Center experience with 100 consecutive patients. Cancer 2007; 110: 62-67.
6. Lopez-Beltran A, Cheng L: Histologic variants of urothelial carcinoma: differential diagnosis and clinical implications. Hum Pathol 2006; 37: 1371-1388.
7. Johansson SL, Borghede G, Holmang S,et al: Micropapillary bladder carcinoma: a clinicopathological study of 20 cases. J Urol 1999; 161: 1798-1802.
8. Kamat AM, Dinney CP, Gee JR,et al: Micropapillary bladder cancer: a review of the University of Texas M.D. Anderson Cancer Center experience with 100 consecutive patients. Cancer 2007; 110: 62-67.
9. Comperat E, Roupret M, Yaxley J, et al. Micropapillary urothelial carcinoma of the urinary bladder: a clinicopathological analysis of 72 cases. Pathology 2010; 42:650–654.
10. Samaratunga H, Khoo K. Micropapillary variant of urothelial carcinoma of the urinary bladder; a clinicopathological and immunohistochemical study. Histopathology 2004; 45:55–64.
16. Ghoneim IA, Miocinovic R, Stephenson AJ, et al. Neoadjuvant systemic therapy or early cystectomy? Single-center analysis of outcomes after therapy for patients with clinically localized micropapillary urothelial carcinoma of the bladder. Urology 2011; 77:867–870.