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The Korean Journal of Pathology 2006;40(4): 263-268.
Clinicopathologic Analysis of the Micropapillary Variant of Urothelial Carcinoma in Urinary.
Kyungji Lee, Ahwon Lee, Yeong Jin Choi, Kyo Young Lee, Chang Suk Kang, Sang In Shim
Department of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea. Klee@catholic.ac.kr
BACKGROUND: Micropapillary urothelial carcinoma of urinary bladder is a rare and aggressive subtype of urothelial carcinoma (UC). METHODS AND RESULTS: Seven UCs with a micropapillary component (MPC) were identified by reviewing 135 cystectomy specimens of UC (5.2% in incidence). MPC was associated with conventional UC in 6 cases and the plasmacytoid variant of UC in 1 case. Lymph node metastasis, that characteristically contained MPC was present in 60% (3 out of 5 cases of regional lymph node dissection). Three patients with extensive MPC showed laminar propria invasion (pT1; 33%) and perivesical fat invasion (pT3; 67%). Two out of 3 patients with extensive MPC showed distant metastasis into the colon after cystectomy. The colonic lesions showed exclusively micropapillary differentiation. Four patients with focal or moderate MPC (pT2, 25%; pT3, 75%) were alive without disease at the time of writing this article. All 3 cases with extensive MPC had surface and/or invasive MPC on the prior TURB specimen. Immunohistochemically, the tumor cells were positive for cytokeratin 7, cytokeratin 20, EMA and E-cadherin and tissue retraction spaces that simulate lymphatic spaces were negative for CD34 in all 7 cases. CONCLUSIONS: This study suggests that the micropapillary growth pattern in UC is a manifestation of aggressive behavior and UC with MPC must be included as part of the differential diagnosis when dealing with a metastatic lesion with a micropaillary structure.
Key Words: Micropapillary; Urothelial carcinoma; Urinary bladder